The real story on Gas Checks

[MakeMineA10mm]

OK, we've had some good discussions about esoteric casting topics, so here's another...

How is it that a Gas Check really works?

I've heard -

1. That it scrapes the lead away that is laid down in the barrel by the front portion of the bullet's passing. (A second similar argument is that it scrapes away lead left in the bore from previous shots...)

2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore...

And, while this isn't a theory - I've also heard that it is permissable to use lead bullets with gas checks in firearms that otherwise aren't supposed to see bare lead, such as the M-1 Carbine or Old-Model Ruger 44 Carbine. Any input on that?
(And, if you do, and say that it does allow this, please explain why/how?)

[Bullshop]

The gas check increases the shear strength of the alloy so can allow higher pressure than the alloy alone. It acts as a drive gear, geared to the land/groove of the barrel and geared to the boolit in reverse, inside the check.
I think it has little to do with sealing the gas, pressure takes care of that. In fact I think a gas check at pressure below or just barely adaquit of what is needed for obturation may prevent a good seal. Depending on how high the pressure is the base is what will obturate to make a seal. The higher the pressure the more length of the bullet will obturate. If pressure is not high enough to obturate past the check you may loose the seal. Most leading problems in revolvers is not from too soft a boolit as many think but just the opposite they are too hard for the pressure used. Read Dave Scovilles book loading the peacmaker for some good info on that. What the gas check is doing is making a harder boolit from a softer one.
With a given hardness of alloy a PB boolit can shoot quite well up to a limit in pressure after that limit it needs a gas check and after that limit it need a harder alloy and after that limit it needs a FLGC.
About your last question I remember when the desert eagle gas operated 44 mag semi auto came out. In their operator manual they said it could be used with cast boolits but only with gas check. I think now they say no cast, why? I have used them and Garrands, and carbines with nothing but cast with no problems with lead build up in the gas systam. Lotsa folks here doing that.
BIC/BS

[45 2.1]

The gas check increases the shear strength of the alloy so can allow higher pressure than the alloy alone. It acts as a drive gear, geared to the land/groove of the barrel and geared to the boolit in reverse, inside the check.
I think it has little to do with sealing the gas, pressure takes care of that. In fact I think a gas check at pressure below or just barely adaquit of what is needed for obturation may prevent a good seal. Depending on how high the pressure is the base is what will obturate to make a seal. The higher the pressure the more length of the bullet will obturate. If pressure is not high enough to obturate past the check you may loose the seal. Most leading problems in revolvers is not from too soft a boolit as many think but just the opposite they are too hard for the pressure used. What the gas check is doing is making a harder boolit from a softer one. In addition to the above, it keeps most of the heat/flame off of the boolit. Filler can do the same thing.

With a given hardness of alloy a PB boolit can shoot quite well up to a limit in pressure after that limit it needs a gas check and after that limit it need a harder alloy and after that limit it needs a FLGC.
Maybe so, maybe not. Filler and freechecs can do the same thing to velocities much higher than you think are possible.

[Bret4207]

I'll keep my opinion to myself for now and see what theories are aired. Thia might make a sticky!

[Boerrancher]

Now, here is my theory and it pretty much is in line with everything posted so far, but I am going to add that with my home grown gas checks, they are formed out of very soft, 16 thou thick aluminum which allows them to obturate slightly as well as the alloy, providing somewhat of a seal. I am in total agreement with Bullshop, a factory gas check will not seal much.

Best wishes from the Boer Ranch,

Joe

[Calamity Jake]

"2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

The hot gasses are not in contact with the base long enough to melt it.

I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.

[ddeaton]

Has anyone done any post shoot detective work? Recovered boolits from a backstop or shot into gel? It would be cool to see what happens. I am gaining info here to start casting for my 308.

[dale2242]

I have shot thousands of gas check boolits through a 30 carbine with no ill effects---dale

[felix]

Powder should be shot at 3600-F for at least a micro-micro second. Low pressure loads prolly will get to 1800-F like was suggested, unless the powder formulation promotes a faster heat rise to make more heat. Powders needs a pre-determined heat or pressure (which is converted into heat) to burn itself properly. Yes, powder granules will be pushed into the boolit base with ease on a naked boolit, and the base will be forced into a concave pattern once the boolit/bullet is moving. ... felix

[jonk]

Well I always felt the name says it all- gas CHECK. It checks, i.e. regulates, the flow of gas to the bullet. (Plasma I suppose, not gas). It's a harder metal than the bullet itself. While I would not have the audacity to disagree with some of the guys here smarter than I, I would question anyone saying that it is to protect the base of the bullet. I've shot many thousands of USGI M2 jacketed bullets with exposed lead core bases of pure lead. That didn't melt even with a full power rifle load. Rather, I think the check is arresting blow by gas. Even if the bullet obdurates properly to the bore, it is still a soft material and that high pressure gas can and does etch its way by the base of the bullet and spalls/etches/cuts/blasts lead off whatever you call it on its way by, causing leading. The gas check, being harder, isn't as prone to the gas blasting by. Same thing for fillers; a large quantity, relatively speaking, of a substance between the bullet and plasma keeps etching/blow by down.

Just my take.

[felix]

Absolutely correct. ... felix

[longbow]

I agree that the heat is applied for too short a time melt a bare lead base as has already been stated. A boolit is only in the barrel for approximately 0.001 of a second for 20" barrel at 1500 FPS.

Hot gases leaking by the sharp edge of the base erode small bits of lead which can be melted/vapourized then redeposited as leading.

Some of my first small bore (.30 cal) cast boolit shooting was with the Lyman 311041 in a .308. I lived in a remote area and didn't have gas checks so loaded without them not ever having had problems with PB boolits in .45-70 Marlin and Siamese Mauser with "J" bullet loads under PB cast boolits.

Well, to my surprise I had .30 cal boolits going sideways through the paper at 50 yards. I dug some out of snow and found that there were literally no lube grooves left and the sides of the boolits were smooth and rounded. This was with a load of IMR 3031 to Lyman load data. I tried lower powder charge but no real improvement. Turns out a neighbour had a box of .30 cal gas checks and gave them to me. Problem solved. Same boolits ACWW with and without gas checks.

In the end I went to IMR 4227 and somewhat lower pressures and velocities with very good results.

In my .44 mag if I push the pressure envelope with PB boolits I find I get gas cutting. Worse with groove size or slightly under groove size boolits but even happens with oversize boolits, just right at the edge of the base and a little ways along the shank.

There is a large pressure drop as the gas leaks around an edge and especially if there is room to expand after the edge. I believe one of the functions of a gas check is to provide that initial pressure drop and a surface that is more erosion resistant to the gas. What I am saying is that it doesn't seal perfectly, it just helps to reduce leakage enough to get the boolit out of the barrel.

Gas checks may also help to rotate the boolit too as some claim but I suspect if true only to a minor degree as the contact area is extremely small. Also, some people claim they have gas checks fall off boolits after the leave the muzzle. If so they can't possibly help rotate the boolit.

Just a couple of thoughts.

Longbow

[snowwolfe]

When should a gas check be used then, if ever? What material should it be made of? Should it be sized the same as the bullet, or bigger, or smaller?

[shotman]

I will make a comment I dont rememberof digging out any boolits with the gas check attached. do any of you? rick

[missionary5155]

"2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

The hot gasses are not in contact with the base long enough to melt it.

I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.

Your experiment is valid in a none presurized situation... You need to duplicate the HEAT plus PRESSURE that occurs inside a barrel.

[missionary5155]

Recovered Gaschecks... I have recovered gas checks still attached to Lee 155 .314 fired from my Chicom SKS fired into a soft sand burn at no more than 50 yards I had on my property yearas ago in West Indiana. All that I learned from them was I could reuse them after opening the mouth a bit.

[sundog]

Couple of thoughts. First, it seems to me that a GC needs to be sized to the same size as the boolit. Larger, and it presents issues with stretching the neck larger than t he boolit thus inducing a problem with neck tension. Of course there is some spring back depending on the condition of the neck. Smaller and, well,... why would you want to?

My other thought is that it is possible for the boolit and check to rotate at different speeds. Even though a check is 'crimped' on, the crimp is radial, not length wise. Push a boolit hard enough and it will strip, not so I think for the hard GC. Nowhere is it written that they have to turn as one.

[Morgan Astorbilt]

I'm sure gas checks "upset" to conform to the bore. I remember seeing somewhere, maybe an old Lyman reloading manual, a photo of a jacketed bullet shot out of a barrel with only a chamber, and the base mushroomed out. A fired bullet, is subject to two inertial forces. When being fired, the base starts to move before the nose, and when if hitting an object, (steel plate), the nose starts to stop before the base.
Morgan

[MT Gianni]

In "The Bullets Flight", I think, it was quoted in Precision Shooting, Dr. Mann wrote of a 30-06 that had blown up due to an excessive charge. The cartridge shot in it was a 270. In order for the action to blow, the pressure had to expand the jacket bullet to groove diameter not just vent past the .031" of gap that existed. I am in the checks expand under pressure camp. I did smear some LY black moly under a check and fire 3 in a 44 once. Recover showed some lube left on them though not as much as I put. I do not consider that scientific by any means but it did teach me the bullet was not in the bore for very long. Gianni

[HeavyMetal]

I'm going to suggest that the gas check does two things, scrapes the bore and adds a bit of help to alloys that may not be up to the presures they are being fired at!

I have seen unburned powder stuck to the base of boolits and think that, because powder burns progressively and does not explode like BP, many time it is it's own filler.

This will be with rifle cartridges of course. Most pistol rounds will use smaller amounts of much faster powders and may see these issues come to light much faster than in a rifle.

How often have we seen the the leading question posted and seen these three suggestions made:
Check hardness, check boolit diameter, and switch to a slower powder?

This is a good thread and I think we'll see some great ideas posted, mine are simply "food for thought"!

[454PB]

My opinion is that's it's a combination of boolit base protection and a scraping action. I did an experiment a while back with some "non conventional" boolit lube that heavily leaded the revolver barrel to the point where 25 yard groups were 8". I then fired a cylinder full of gas checked boolits, and not only was the leading removed, the groups shrank to 1.5".

[Lloyd Smale]

i agree with the scraping action theroy. A gas checked bullet will clean out leading as well as a jacketed bullet will. I personaly think its a combination of that and when the base bumps up (I hate that terminology) it creates a much better seal then any lead alloy can to resist gasses from leaking by. I also think it gives a perfect base for gases to press against in a consistant manner and aids in accuracy because of this.

[Bullshop]

I dont know bout the boolit and check not being in sink. If that were so the land cuts in the boolit would show wider than in the check You see that on revolver boolits on the forward band where the boolit didnt begin to turn until more of its bearing surface was engauged. You never see it at the base. On the base band the land cuts will be the same as on the check.
Once that boolit is in the rifling the check is crimped and is geared to the boolit. Dont matter what it does after it leaves the barrel only when its in there. It can fall away because it already did its job.
Same thing with PP, it falls away once out the barrel but it surnuf was driving the boolit.
You will find land cuts on the boolit for the length of the papar bearing surface.
If that check is not geared to the boolit when under pressure then what is it that holds a soft boolit that is fired beyond its pressure limit without a check. If you fire a pure lead boolit with a check way beyond a pressure that pure lead can handle, kinda like the first factory 44 mag ammo it shoots OK because why? Its not because the check is cleaning the barrel its because its holding the boolit in the rifling. Yea yea yea it does other things too like protect the base and yata yata yata but it has to offer machanicle advantage to holding on the rifling. It has to do more than just check gas. I am gonna stick with the drive gear idea.
BIC/BS

[kirb]

So all of this being said what is advantage of annealing (sp) gas checks. I have read hear of putting them in a pipe nipple and putting in you a wood stove for a while. are many of you using annealed checks. Does making the check softer give it a better hold on the bullet or a better bite in the rifling.

Kirb

[docone31]

It eliminates spring back.
sometimes, when the check is sized on, it can open up. Annealing allows the check to be sized on, and stay there.

[BD]

I'm pretty much in agreement with most of what's been said. I'll add that I've recovered a fair number of boolits with the check still on the base, 6.5x55 , .357 and .44 mag, both from berms and animals. However, not all of them in any given session retained the checks.

I'll also add that checks can limit the lead build up on the face of revolver cylinders significantly. Especially true in revolters like the Redhawks with oversize chamber throats, (.432). I've had Redhawks in which the cylinder would bind after less than 100 rounds of naked cast, but could spit out thousands of checked bullets without binding. So some base protection occurs, at least in revolters.

IMO this is another one of those areas in which individual firearms can be a law unto themselves, so many varibles are in play that it's tough to make any kind of blanket judgement as to what is occurring in any individual situation.

My preference in something like a full house .44 mag load is a tight check on a stout rear drive band with a lube groove just forward of the crimped on check. It just seems like that arrangement can pass down the barrel thousands of times with consistent accuracy, no barrel leading and no cylinder binding.

BD

[45nut]

IMO this is another one of those areas in which individual firearms can be a law unto themselves, so many varibles are in play that it's tough to make any kind of blanket judgement as to what is occurring in any individual situation.

I submit ALL firearms are individuals and respond accordingly to the individual cartridges fired.
Manufacturing tolerances are such that it cannot be otherwise.

[jhalcott]

I don't believe Gas checks are needed for MOST handgun loads. even the 44 mag CAN get by with out one. It's in the hi pressure loads that gas checks come into their own. Hi pressure and NOT hi velocity is the key. I've shot 1000's of them in lots of guns trying for ultra hi speeds. I have found checks on the base of most bullets when crimp ons were used. Even some lyman non clip on checks stayed on when shooting into some wet pack media. I had a chance to shoot some sick goats with cast bullets and studied the remains for evidence of the effects of shooting them. I can't say there was any thing UN expected in the remains.

[MakeMineA10mm]

I love this place! You guys are great.

TONS of great information here. I'll be re-reading it in the future for sure!

[44man]

I dont know bout the boolit and check not being in sink. If that were so the land cuts in the boolit would show wider than in the check You see that on revolver boolits on the forward band where the boolit didnt begin to turn until more of its bearing surface was engauged. You never see it at the base. On the base band the land cuts will be the same as on the check.
Once that boolit is in the rifling the check is crimped and is geared to the boolit. Dont matter what it does after it leaves the barrel only when its in there. It can fall away because it already did its job.
Same thing with PP, it falls away once out the barrel but it surnuf was driving the boolit.
You will find land cuts on the boolit for the length of the papar bearing surface.
If that check is not geared to the boolit when under pressure then what is it that holds a soft boolit that is fired beyond its pressure limit without a check. If you fire a pure lead boolit with a check way beyond a pressure that pure lead can handle, kinda like the first factory 44 mag ammo it shoots OK because why? Its not because the check is cleaning the barrel its because its holding the boolit in the rifling. Yea yea yea it does other things too like protect the base and yata yata yata but it has to offer machanicle advantage to holding on the rifling. It has to do more than just check gas. I am gonna stick with the drive gear idea.
BIC/BS
Have you been reading all of my posts again? :coffee:
I have NEVER seen a melted boolit base and I shoot hard cast PB at high pressures where the land marks on the base are land width. Shoot a soft boolit so it doesn't grip the rifling at the base and you need a check.
The thing was not named right, it should have been called a hard drive band! :drinks: Of course it will scrape out lead from skidding boolits. When it gears to the lands and grooves, it has no gaps.
Guess what? Fit a hard cast that doesn't skid and it will ALSO clean out leading.
I know a lot of you have had poor fitting gas checked boolits that leaded the crap out of your barrels. Also gas cut boolits when gas got past the under size checks and boolits.
Bullshop, the ONLY thing I disagree with is when a check drops off some boolits and not others. I want it to stay on until the target is hit. If EVERY one dropped into the same pile in front of the muzzle, it would be OK, but they won't. Keep them on the boolit.

[Bullshop]

44man
Maybe I didnt say what I ment. I didnt mean to say it was good if the checks fell off after the boolit leaves the barrel what I ment was that even if they do fall off they were still driving the boolit when they were under pressure in the barrel. If it springs back and is blown off like a paper patch when it exits it has still done its job in the barrel.
As to accuracy since you cant get them to all fall in the same place like a PP it is best if they stay on.
BIC/BS

[MTWeatherman]

All else being equal, it’s a rare firearm indeed that shoots a PB bullet more accurately than a gas checked one. With proper pressures, good barrels etc...equally well yes...but rarely better.

Gas checked bullets allow increased velocity performance in nearly all rifles and some magnum class handguns... exceptions largely being those designed for black powder where pressures must be held low... well within the strength of a non-checked bullet.

Largely repeating what others have already said...but since the question was asked, I believe gas checks yield those positive results primarily in 4 ways. Gas checks:

1. Provide a scraping action to remove lead. This allows some leading to occur as each bullet is fired...the gas check restores the barrel to its pre-fired unleaded condition and prepares the barrel for the next shot.

2. Eliminate or greatly reduce gas cutting...important in higher pressure loads and in firearms with somewhat undersized cast bullets, large throats, wide spots in the barrel etc. This is accomplished by the greater yield strength and melting temperature of the gas check. Note some gas cutting or leading could still occur as long as it is not enough to overwhelm the scraping action of point 1 or the riflings abillity to grip the bullet.

3. Provides increased bullet yield or shear strength for the rifling by replacing what would otherwise be lead with a copper alloy. In many cases, this also results in more bearing surface providing additional strength.

4. Provides a uniform base to the bullet...important as the bullet exits the barrel. Non-uniform bases adversely affect accuracy...always a possibility with PB bullets unless care is used in casting and seating.

(A contributor to both effects 1 and 2 above may be the “spring back” quality of the check and likely expansion of the check itself that takes place when pressure forces out any air remaining between the check and the shank and obturates the shank itself.) This would enhance the scraping and sealing qualities of the check.

Gas checks do not accomplish their mission by preventing the melting of the base...far too little time exposure to accomplish this by temperature alone. Exposed lead bases in jacketed bullets fired under high pressure have long ago refuted this theory. It is high velocity gas cutting along the sides of the bullet which erode and destroy the bearing surface. This lead is then condensed in the barrel ahead of the bullet as the pressure and temperature drops.

What effect(s) comes into play is dependent on the bullet, load (read pressure), firearm, lube, etc.. Low enough pressure in a smooth barrel with a proper fitted boolit with good lube and nothing is to be gained by the check. None of the 4 points above are necessary. However, as pressure goes up, barrel quality goes down, bullet quality and lube deteriorates (to include loss of bullet bearing surface and size), etc. and some or all of the above become important.

In short, a gas check allows many things to be less than perfect while maintaining acceptable accuracy and higher performance and velocities than we could otherwise achieve without it. In many cases it makes life much easier for the casting novice as it reduces the need for the more extensive testing with bullets, lubes, and loads that would otherwise be required...to say nothing of bore lapping.

[Boomer Mikey]

Gas checks are scrapers and heat shields that extend the useful range of pressure a bullet alloy can work within by strengthening the bullet's base to reduce skidding/stripping and control of lead deposits (scraping). The gas check also controls fusion caused by large amounts of fast burning pistol powder.

When pressures are high and bullets soft, bullets skid or strip in the rifling.

When pressures are low and bullets hard there's no obturation to keep gasses from from blowing by the bullets base even if gas checks are used. Lube is lost and friction leaves lead deposits too great for the scraper to control.

For good loads, pressure and alloy hardness should be coordinated. Using the formula 1422 x BHN will provide the minimum pressure yield point for your alloy. Lyman #2 and WW air cooled alloy are typically BHN 14-15 so starting loads should be selected that develop at least 20K psi to provide a gas seal... obturation. When pressure is increased to the point that the gas check can no longer control the amount of lead being stripped from the bullet maximum velocity for your load combination has been reached.

To find the bullet hardness desired, divide the working pressure by 1422... 35K psi / 1422 = BHN 24.6 or less.

Boomer :Fire:

[gon2shoot]

I never considered a check as a scraper, I have cleaned highly leaded barrels (revolver) with a hard PB boolit.
I have also leaded barrels with an ill-fitting hard boolit, I use checks to reduce gas cutting at higher pressures.

There's some good thoughts here guys, keepem coming. :-D

[Bret4207]

All else being equal, it’s a rare firearm indeed that shoots a PB bullet more accurately than a gas checked one. With proper pressures, good barrels etc...equally well yes...but rarely better.

Gas checked bullets allow increased velocity performance in nearly all rifles and some magnum class handguns... exceptions largely being those designed for black powder where pressures must be held low... well within the strength of a non-checked bullet.

Largely repeating what others have already said...but since the question was asked, I believe gas checks yield those positive results primarily in 4 ways. Gas checks:

1. Provide a scraping action to remove lead. This allows some leading to occur as each bullet is fired...the gas check restores the barrel to its pre-fired unleaded condition and prepares the barrel for the next shot.

2. Eliminate or greatly reduce gas cutting...important in higher pressure loads and in firearms with somewhat undersized cast bullets, large throats, wide spots in the barrel etc. This is accomplished by the greater yield strength and melting temperature of the gas check. Note some gas cutting or leading could still occur as long as it is not enough to overwhelm the scraping action of point 1 or the riflings abillity to grip the bullet.

3. Provides increased bullet yield or shear strength for the rifling by replacing what would otherwise be lead with a copper alloy. In many cases, this also results in more bearing surface providing additional strength.

4. Provides a uniform base to the bullet...important as the bullet exits the barrel. Non-uniform bases adversely affect accuracy...always a possibility with PB bullets unless care is used in casting and seating.

(A contributor to both effects 1 and 2 above may be the “spring back” quality of the check and likely expansion of the check itself that takes place when pressure forces out any air remaining between the check and the shank and obturates the shank itself.) This would enhance the scraping and sealing qualities of the check.

Gas checks do not accomplish their mission by preventing the melting of the base...far too little time exposure to accomplish this by temperature alone. Exposed lead bases in jacketed bullets fired under high pressure have long ago refuted this theory. It is high velocity gas cutting along the sides of the bullet which erode and destroy the bearing surface. This lead is then condensed in the barrel ahead of the bullet as the pressure and temperature drops.

What effect(s) comes into play is dependent on the bullet, load (read pressure), firearm, lube, etc.. Low enough pressure in a smooth barrel with a proper fitted boolit with good lube and nothing is to be gained by the check. None of the 4 points above are necessary. However, as pressure goes up, barrel quality goes down, bullet quality and lube deteriorates (to include loss of bullet bearing surface and size), etc. and some or all of the above become important.

In short, a gas check allows many things to be less than perfect while maintaining acceptable accuracy and higher performance and velocities than we could otherwise achieve without it. In many cases it makes life much easier for the casting novice as it reduces the need for the more extensive testing with bullets, lubes, and loads that would otherwise be required...to say nothing of bore lapping.

You covered every point I would have made. :drinks: The only thing I would add is it takes a proper fitting GC to get the benefits of a GC. Put one on lopsided or use one that is too small for the bore and all you did is waste your money. There'll be no scraping action with an undersized GC or one where the edge of the GC isn't meeting the lands at least. Instead you'll get a burnishing action that will sort of iron the leading into the barrel. Took me a while to figure that one out on an oversized/worn 8mm barrel.

[runfiverun]

with good bbls i use the g/c to protect the base of the boolit and fill the area in front of it with lube, as the lube will act as a hydraulic seal and should stop the scraping action.
in other guns i leave the area open so that the check has an area to scrape lead into.
now is it actually spraping lead into this area, i hope not.
i would hope i have fit the boolit to the gun well enough. but a lot of the g/c designs move the lube grooves forward and the pressure doesn't seem to hydraulic the lube as well.
this i think is why your velocities are kept lower with a g/c design not fired with the g/c.
then it would be with a p/b design.

[Newtire]

I'm saying it makes for a flat base so as to have even forces pushing on the base of the boolit as it leaves the muzzle. Without it, at too high of pressure, would be just about like shooting out of a barrel with a bad crown.

Just a guestimation..

Now that someone mentioned the paper patched boolits...I have never done up any of those but from looking at them, the base of that paper isn't exactly flat looking with that little twist on it. Now I don't have any idea!
I also have fired many rounds thru my carbine. You get a little lead on the gas piston after a few hundred rounds maybe but no big deal. I also have shot the Ruger Deerfield with numerous cast boolits and haven't seen any buildup of lead after almost 200 rounds. I get more crud from the lube than anything. The carbine is a snap to clean and the Ruger requires a bit of patience.

[Lloyd Smale]

Just an estimation was about the best statement yet. Its one of those questions like what does bullet lube do? Nobody has the right or wrong answer because nobody really knows the total story. All i know is gas checked bullets are usually easier to get to shoot accurately and i guess thats good enough for me.
I'm saying it makes for a flat base so as to have even forces pushing on the base of the boolit as it leaves the muzzle. Without it, at too high of pressure, would be just about like shooting out of a barrel with a bad crown.

Just a guestimation..

I also have fired many rounds thru my carbine. You get a little lead on the gas piston after a few hundred rounds maybe but no big deal. I also have shot the Ruger Deerfield with numerous cast boolits and haven't seen any buildup of lead after almost 200 rounds. I get more crud from the lube than anything. The carbine is a snap to clean and the Ruger requires a bit of patience.

[MTWeatherman]

The only thing I would add is it takes a proper fitting GC to get the benefits of a GC. Put one on lopsided or use one that is too small for the bore and all you did is waste your money. There'll be no scraping action with an undersized GC or one where the edge of the GC isn't meeting the lands at least. Instead you'll get a burnishing action that will sort of iron the leading into the barrel. Took me a while to figure that one out on an oversized/worn 8mm barrel.


Good point.

You also indirectly pointed out the two major disadvantages of gas checks...the required investment of time and money.

Care must be exercised in seating each check squarely on the base...not done correctly and there goes your uniform base and accuracy along with it. Slows production time to much below what a simple resizing and lubrication of a PB would be...and eliminates the simple method of using an unsized bullet with tumble lube..

Checks require an investment of money in a resizing die to seat and size those checks and those checks are no longer of small cost themselves. They've gone up significantly in price over the past couple of years...now 2 1/2 to 5 cents apiece for most calibers. Though the cost of copper has now fallen to near the levels of 5 years ago, I have yet to see this passed on in the reduction of gas check prices. Cynic that I am...I don't expect to see much reduction either. With Hornady essentially having a monopoly on them (they make Lyman as well and except for the GB Gators, there is no competition), there is no reason to drop prices...no real competition to force them back down.

So...all is not positive with checks. If a PB boolet fits your needs, makes sense not to use a GC design.

[JIMinPHX]

I’m on board with most of what has been said already. I just thought that I would submit a few pictures to show what I’ve seen. The first one shows the basses of some 150-grain PB semi-wadcutters. The ones on the right in that first picture were pushed to 1250fps by a warm charge of H-110. The heavy cratering on the bases makes me think that this charge should be used with a GC. The ones on the left show what I get when I push the same boolit with Bullseye or Unique.

The next two pictures show some recovered .223 slugs. Even at 2600fps, I still find some boolits with the GC still attached, although about 85% of them do come off. The ones that come off almost invariably are found in the target near the spot where the boolit stops. This is true if I am shooting at crumb rubber or game animals. I am pretty sure that my GCs are still attached when they hit the target. Other people with looser fitting checks may have different experiences, but this is what I see with mine.

[cbrick]

Great thread, it should be a sticky.

Like every response in this thread I too have my SWAGS.

Such as the check holding the boolit to the rifling. SWAG . . . the check is the last part of the boolit to enter the rifling, if the boolit is not already turning at the twist rate of the barrel and requires the check to do this I would think you have far worse problems than a possible benefit or detriment of the check. I wouldn't want to have to try and clean that barrel . . . gas check or not.

I don’t believe for a second that being a “heat shield” is any part of the function of a check. Lead absorbs heat very slowly; much to slow for the micro second it’s in the bore to “melt” the alloy. If the heat of the burning gas could melt lead why doesn’t paper or plastic shotgun wads melt or burn? Or even discolor them? Copper, or worse yet aluminum checks absorbs heat far faster than does lead (and aluminum checks do work) so how could a check be a “heat . . . “shield”?

Let’s say you have an extremely high quality bore and your rifling starts off at .030” wide. Even the best made barrels cannot maintain that .030” perfectly for the length of the bore, at some point it’s going to narrow a bit to say .027” and then widen to say .031”. Once the boolit is engraved to .030” and then reaches the narrower part high pressure gas leaks by with the very same effect as an acetylene torch cutting steel. This is NOT melting, it is a high pressure abrasive gas cutting and stripping it. This is where a check, a properly functioning lube AND A PROPERLY FITTED BOOLIT of a SOFT ENOUGH ALLOY for the pressure can have a big effect at reducing or stopping leading. Too hard is in all probability the cause of more leading than using or not using a check. Too soft an alloy usually gets the blame but too hard is more often than not the cause but even this to a large degree can be minimized by a properly fitting boolit. A poor fit and too hard an alloy and there’s trouble in paradise, gas check or not. In addition to sizing the checks I am completely anal when casting, boolit bases for long range loads, i'ts a perfect base or it's no better than a sprue regardless of what the rest of the boolit may look like.

I am a firm believer that checks must be fitted flat against the base of a perfect/flat/square boolit base. The higher the velocity and the longer the range the more important this becomes. If a check is installed crooked, think of that last instant as the boolit leaves the bore (think freeze frame photo) and one side of the check is still in contact with “one side of the rifling” by only a few thousands of an inch but because of the crooked check the other side is free of the bore completely. There is still pressure pushing the boolit, not peak pressure but pressure none the less so where is the boolit going? Two things I can be reasonably sure of; 1> not straight and 2> not where you want it to go. I have made up punches to size checks flat (taking out the concave) and slightly flaring the sides of the cup. They slip on fully and easily, fit flat and crimp on tight.

I think the check does help scrape the bore and helps keep it cleaner by scraping powder, lube and any minor leading from the previous shot. I think the checks adds strength to the boolit base and helps minimize base deformation which would allow higher pressures to be used.

These are some of my SWAGS on checks and I’m sticking to them . . . right up until I change my mind.

Rick

[keeak]

:confused:Ok, then here is the next question. If you eliminate the gas check and just use a filler will that load A) shoot accurately, B) produce leading to a significant degree, all assuming a #2 alloy???

[longbow]

I haven't pushed the limits using filler but have gotten very good results with moderate loads in my .303 British under plain base boolits and 314299's without gas check. I was getting leading even with gas check before adding filler. Using loads with filler has allowed me to get the same performance as gas check loads without the gas check and no leading.

I don't have any "proof" at this point, just opinion, but I have read a couple of articles that say much the same.

A side by side comparison test would have to be done to get any kind of consistent results for various loads, velocities and pressures. In fact many tests would have to be done to get "proof": hard versus soft boolits, fast versus slow powders, different diameters, different weights, different checks, different fillers, etc.

Fillers seem to work for some people and not for others and they may not be suitable in some cartridges especially those with large body, small neck and steep shoulder.

If I get time this summer I will try to run a test of gas check versus filler loads in my .303 from say 1600 - 1800 FPS up to where things go bad. I have loading data for up to at least 2250 FPS for gas checked boolits.

If I get this done it will be limited to my gun and the powders and boolits I have available. I have been wanting to do this anyway so maybe this thread will get me kick started! I haven't been shooting near enough for a while.

Longbow

[mtgrs737]

IMHO the only thing gas checks do to a1600fps or under boolit is lighten my wallet! And I am much too tight to allow that! LOL!

Sorry for the humor in a very serious thread! :)

[HangFireW8]

"2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

The hot gasses are not in contact with the base long enough to melt it.

I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.

I just found this and have to comment on it.

Did you run that cutting torch at 20,000 PSI, and then focus that pressure a few thousandths wide right on the edge of the bullet base?

If not, you've tested something, but you've proven nothing about what goes on in a barrel.

-HF

[dromia]

Another intelligent, informative thread based on actual knowledge and experience, Cast Boolits at its best. :drinks:

Stickied!:-D

[Gee_Wizz01]

I have also been pondering on the hows and whys of gas checks. I know they work, as I have seen the results. I have always tried to seat them square with the base, but I have often wondered how much effect it would have, when the base of the bullet gets hit with 25,000 to 30,000 PSI. I have shot many thousands of bullets with gas checks and have recovered hundreds of them and have several findings; 1. Hornady crimp on gas checks seem to stay put on the bullet into the berm. 2. I fired some very old Lyman slip on gas checks in my .44 mag rifle and a good number of them came off in flight, I found most of them about 10 yards down range. 3. In my .44 Mag I sized the bullets to .431 and the Hornady gas checks measure .431 at the front edge, the Lyman checks measured about .429 at the front edge, both shot accurately and neither loads caused any leading. I recently got some freechex in both .44 and .30 calibers. The free chex are smaller in diameter than Hornady gas checks, but seem to function well, I am still testing these to see if they are as accurate as Hornady. The more I think about gas checks, the more unanswered questions I have.


G

[armyrat1970]

As a relative *** to this site this thread has given me much for thought. I am trying to work up some loads for my 8x57 with Milsurp primed cases that I have pulled the bullets and powder from. I will be using the primed cases and pulled powder under my Lee 175gr.RN cast bullet with #2. Have often wondered about the need for gas checks. It may take some time before I actually get these loads together but I will try some checked and some un-checked and see what the results are comparing velocity, accuracy, leading and just overall performance. (Doubt I will be able to recover any of the boolits fired but I will try) I will also use a filler (lint) for some and no filler for others to compare the need for such. Interesting experiment as I will have some gas checked with and without a filler and some un-checked with and without a filler. Also sized and unsized boolits. As I said it may take awhile before I get all of the results but will post back when I do.
Great thread with a lot of good input.

[Bret4207]

:confused:Ok, then here is the next question. If you eliminate the gas check and just use a filler will that load A) shoot accurately, B) produce leading to a significant degree, all assuming a #2 alloy???

It all depends, or as we say up here, " 'pendz on". What cartridge, what load combo, what design boolit, does it fit right in the first place, etc., etc. If you were talking a 32-40 at 1450 fps for instance, yeah it might well work just fine. If you were talking a 22-250 at 2000 fps you might just as well stop now as fillers don;t generally work too well in cases of that shape.

Gotta be a bit more specific to say one way or the other.

[Bret4207]

I just found this and have to comment on it.

Did you run that cutting torch at 20,000 PSI, and then focus that pressure a few thousandths wide right on the edge of the bullet base?

If not, you've tested something, but you've proven nothing about what goes on in a barrel.

-HF

Applying it to the edge isn't duplicating a barrel either. The whole base is under pressure. But I know what you're saying. That's why I like to add all those little qualifiers like, "it seems to indicate" or "the theory is...".

Until one of use can get inside a barrel and watch it's all theory.

[armyrat1970]

I just found this and have to comment on it.

Did you run that cutting torch at 20,000 PSI, and then focus that pressure a few thousandths wide right on the edge of the bullet base?

If not, you've tested something, but you've proven nothing about what goes on in a barrel.

-HF

I'm an old weldor and fitter by trade. You don't run a cutting torch any where near that pressure to begin with. Not even in the hundreds. You don't have anywhere near that amount of pressure in any of the oxygen or different type of gas bottles you may be using.

[303Guy]

This boolit was fired with a case filler but without the gas check. The gas check rebate should theoretically have been subjected to equal pressure in all direction but the peening shows that did not happen. I have other PB that show 'sand blasting' marks. This would indicate that the boolit is not being subject to a plasma but rather, burning granules of powder. (The plasma is there all right but so is a lot of burning granules of powder).
http://i388.photobucket.com/albums/oo327/303Guy/MVC-009F.jpg

This next boolit was a bit different in that its base was protected by a wax sabot.
http://i388.photobucket.com/albums/oo327/303Guy/MVC-008F.jpg

Both boolits were paper patched.

This boolit was loaded without filler (and also no g/c). Flame cutting is exacly where it is to be expected - the groove ridge.
http://i388.photobucket.com/albums/oo327/303Guy/MVC-886F.jpg

Here we have boolit with the rifling 'ridge' somewhat narrower than the groove in the barrel. The lead section has the same 'wear' as the gas check.
http://i388.photobucket.com/albums/oo327/303Guy/MVC-644F.jpg

This one shows base deformation due to boolit displacement in the bore.
http://i388.photobucket.com/albums/oo327/303Guy/MVC-640F.jpg

And without the gas check - same thing (just worse) - but no gas cutting.
http://i388.photobucket.com/albums/oo327/303Guy/MVC-568F.jpg

I'm not sure what to make of it all.

[MakeMineA10mm]

Wow. This has given me more to chew on than I expected, and I'm still not sure we're at the end...


Part of the problem may be too many variables. Maybe if we can analyize one set of circumstances, we can then address variables from there.

Taking Rick's idea of a freeze-frame photo a little farther, let's go SUPER-SLOW-MOTION in the firing of the cartridge with a gas-checked boolit...

First, let's assume that the loaded round is perfect - bell-mouthing, seating, and crimping all went well, so we have an ideal, non-deformed boolit loaded concentrically in the case.

Second, let's assume that we used a flat or flattened gas check that is perfectly flush and flat against a perfect boolit base. Nothing out-of-balance or alignment.

Third, let's assume it is a crimp-on gas-check, so we needn't debate the issue of it coming off at this point in time.

Fourth, let's assume we've sized the boolit (and GC) to throat size, and the barrel is .001" smaller in groove diameter than the chamber's throat. (i.e. "perfect")

So, here we are waiting for the hammer to fall.

I guess the first point we have to address is what kind of cartridge is this and what kind of powder load are we using? Let's say it's a 44 Magnum with Elmer's classic load of 22.0grs of 2400 powder with the Thompson 250gr SWC boolit.

With this we have at least two circumstances we will have to vary latter on: First, we have a medium-sized load of powder (well above loads of Unique, W231, Bullseye, but well below loads of 3031 or RL-7 in a rifle cartridge). Second, we have a straight-walled case of bore diameter, so the expansion ratio is pretty low (vs. a necked rifle cartridge where a lot of gas/pressure/heat/powder granules are funnelled into a smaller place).

Hammer falls, primer goes off, powder at the rear of the powder load ignites and begins to release large amounts of energy. This increases heat and pressure inside the case and the gases energetically move around the un-ignited granules of powder. Obviously, these conditions all act on the base of the boolit via the gas check.

At some point while all of this is going on and heat and pressure continues to rise and more of the granules ignite, the pressure inside the case causes the bullet to overcome the restraint of inertia and the crimp. The boolit begins to move forward. (Now, I think there are lots of questions that need answered here... Like, what percentage of the powder load is ignited and letting off gas, what percentage is still un-ignited granules and what percentage have completely combusted and converted to gas??? -- All of these will have an effect on the torture being given to the boolit's base...)

Someone who knows more than me, take over from here.... :veryconfu

[techlava]

The gas check increases the shear strength of the alloy so can allow higher pressure than the alloy alone. It acts as a drive gear, geared to the land/groove of the barrel and geared to the boolit in reverse, inside the check.
I think it has little to do with sealing the gas, pressure takes care of that. In fact I think a gas check at pressure below or just barely adaquit of what is needed for obturation may prevent a good seal. Depending on how high the pressure is the base is what will obturate to make a seal. The higher the pressure the more length of the bullet will obturate. If pressure is not high enough to obturate past the check you may loose the seal. Most leading problems in revolvers is not from too soft a boolit as many think but just the opposite they are too hard for the pressure used. Read Dave Scovilles book loading the peacmaker for some good info on that. What the gas check is doing is making a harder boolit from a softer one.
With a given hardness of alloy a PB boolit can shoot quite well up to a limit in pressure after that limit it needs a gas check and after that limit it need a harder alloy and after that limit it needs a FLGC.
About your last question I remember when the desert eagle gas operated 44 mag semi auto came out. In their operator manual they said it could be used with cast boolits but only with gas check. I think now they say no cast, why? I have used them and Garrands, and carbines with nothing but cast with no problems with lead build up in the gas systam. Lotsa folks here doing that.
BIC/BS

A FLMJ is practically a jacketed bullet. Why can't a thin wall tubing and GC make a FLGC that is easy to use and effective?

[Big Dog]

evening all, I'm new to this forum but would like to share some facts about metal, heat & pressure. You see I had worked in the aluminum extrusion industry for 15 years and I learned a few things in that time.

First to allow you all to try to get on the same page of thought, look at a child's Play-Doh factory. You take a hunk of the doh and work it back and forth, while transferring the heat from your hands to help soften it. Then you place it in the factory and press the lever down forcing the doh through a "die" , so basically under heat and pressure the doh
"flows" through the die forming to the die shape.

Now to aluminum, you take a billet (a log of aluminum) and heat it to about 900 degrees F and force it through a heated die at about 2800 to 3500 PSI, and under the heat and pressure (and don't forget that you create heat in the die by friction) and the aluminum flows through the die to the form and size you want. Things to be considered also are alloy, die wall thickness, how clean the metal is (dirt is a killer of dies) the speed at which you force the metal through the die (this will dramatically increase the buildup on the die and force you to pull the die from production) and other small things to boot.

So the things to keep in mind are these:
alloy
heat
pressure
speed
friction & dirt

its all about doing a balancing act ....... try to keep these things in mind when developing a pet load for your use.

How well you figure your alloy % is a factor

How hot you choose to load

How much pressure you get with the load

How fast you choose to push the bullet

How well the fit/size diameter, lube and how well you drossed

OK, now does everyone feel like they are on the high wire ???

[runfiverun]

you forgot time/pressure curve or how long the powder pushes against the base of the boolit.

[Idaho Sharpshooter]

I have a Wildey in 45 Win Mag. Think of it as a 45 acp case 1.198" long. They warn against using even GC lead bullets as the ports bleed off pressure to operate the pistol. If I get to tinkering and the lead bits clog those ports, how might I clean them? With a $1500 autopistol I hesitate to do something that might lead me to having to "fess up" and send the assembly back to Wildey for cleaning.

Rich
DRSS

[shotman]

you will get that I found that Kroil works {thats from my moulds} I have a S&W 460 and put about 200 lead through it .
They have extra compendator for lead. It will LEAD bad. After 2 hrs the first time . I soaked it in Kroil and next time about 10min and was cleaned.

[lwknight]

This is a great thread!!
I started trying to learn this gas check business 30 something years ago and its still ambigues at best.

From all what I read here and other places and my own exp, I gather a few rule of thumbs. Or rules of thumb whatever....

1. The appearant abrasions in the bottom of the naked bullet are actually powder being pressed into the bullet. This will be most noticable in full capacity loads where the ingited powder gas actually forces the powder next to the bullet to extreme inertial pressure against the heavier bullet.. It is not powder burn at all.

2. Gas checks can gear to the rifling even when the bullet skids a bit or even a lot, therefore is able to actually scrape some lead off the barrel.

3. Poor boollit fit and too hard and too hard boolits are bad things.

4. Leading usually starts at the forcing cone and starts smearing farther down the more you shoot.

5. Good lube is as important as oil in your cars engine.

I think and would hope that the GC does have some springback so it will scrape the barrel, if that really does happen.:?

I think that it is possible in some cases that the checks do in fact help seal the bore untill onturation takes effect. At which pointthe gas check no longer matters.

Everything else is still up in the air.:-|
Anyone else get any rules of thumbs from all this and other places?

[Two401Pm]

I will make a comment I dont rememberof digging out any boolits with the gas check attached. do any of you? rick



Yes always the gas check is still attached to the base of the boolit. and sometimes there is still a little lube left in the lube grooves. this is in a 41 mag, 45 colt,and in the sub calibers--357mag, and the 44 mag.

[DukeInFlorida]

I think I have read all of this discussion, and can't recall where anyone mentioned the effect of friction of the barrel on the cast lead bullet. The surface friction at speeds over 1000 is enough to melt the surface skin of the lead. Once the skin is melted, then gas jets can blow through.

The gas checks don't stop the melting of the lead skin due to friction. But they do scrape that melted lead along in front of it, and hydraulically the liquid skin of lead stays where it started, eventually solidifying.

The gas checks also seal the melted skin of lead from the gas jets otherwise seeking to blow past it.

Just my opinion, and I am sticking to it.

[cbrick]

Only problem with that theory Duke is that the lead does not melt. Lead absorbs heat very slowly and it is not in the bore nearly long enough to get hot enough to melt. It can be blasted off the sides of a poor fitting boolit much as an acetylene torch cuts steel but melt it doesn't.

Some people think that the check prevents the hot burning powder gases from "melting" the base of the boolit. If that were true why doesn't paper or plastic shotgun wads show any signs of burning or melting? Cast boolits do not "melt" in your firearm.

Rick

[Franklin Zeman]

Just a bit more "food for thought". When Handloader Magazine was fairly new, there was an experiment shooting lead boolits from a revolver with no barrel attached. So, the slug was only impacted by the pressure and the cylinder. The pictures of the boolits looked like mushrooms. I don't recall the caliber or pressure levels involved. The amount of mushrooming had to involve what happened after exiting the cylinder. Gives some idea of the effects the pressure is causing down stream. Maybe someone can find the article and share more info.

[castormd]

What year was that article in "handloader"?:coffee:

[Franklin Zeman]

I found my old list of index subjects, which is valid from issue #1 up thru 1996. I will see if I can ferret out the article and will post it if I can find it.

[lesslethal]

This is my first post comment. I was hoping to get at least just one of my many questions answered, but golleeee, This one thread was like goin' to college. Man did I ever find the
right place. Oh-boy!!

[Nose Dive]

YEa buddy!You come to the right place if you want "opinions" from the folks that know!

I 'check' cause that is the way I was taught. Bit more bother, but never had a big leading issue and have 'overloaded' like a dummy. I soften my checks too. Why? Well, that is the way I was taught. So your guestion now is "do I do everything the way I was taught"? Well No. I have learned abit, (from these pages on this site!), and employ my education every where I can. {I was taught to 'Hog Tallow" paper patches on 45-70 Trap door rounds!} There is more 'folklore' out there than one can imagine. That is why I love this site!...

There is a lot to consider when boolit making, reloading and shooting. As noted above, listen to the experts, be smart enought to identify them, and follow safety procedures in all that you do. Making your own is a kick.... It is fun, if you are not hurting. Safety. Safety, Safety. There,,,, I have told you three times..... Nose Dive....

[Newtire]

I have been reading some postings on shotgun slug loading and the ones that get the best accuracy in smoothbore barrels have a heavy card wad under the slug. I think maybe this acts similar to the way a gas check does when the projectile leaves the barrel in that it is a flat platform under the slug to alolow an even push out the muzzle so the slug doesn't cant on exit and fly off into never-never land.

[Molly]

I will make a comment I dont rememberof digging out any boolits with the gas check attached. do any of you? rick

I don't recall digging out a cast bullet that failed to keep its gas check, and I loaded them hot in a 30-06.

[Newtire]

I don't recall digging out a cast bullet that failed to keep its gas check, and I loaded them hot in a 30-06.

I have seen some that stay on and some that fall off.

[HangFireW8]

I don't recall digging out a cast bullet that failed to keep its gas check, and I loaded them hot in a 30-06.

Try some old Lyman press-on (as opposed to modern crimp-on) gas checks. Sometimes you get two holes in the target for the price of one!

-HF

[blaser.306]

I've found lots of gas checks flatened out or inverted at the steel backstop . I don't have any question that they stay attached after launch ! After all they are re-seated with a several thousand pound sledgehammer at firing!!!!!

[Molly]

Try some old Lyman press-on (as opposed to modern crimp-on) gas checks. Sometimes you get to holes in the target for the price of one!-HF

Hi Hangfire,

Believe it or not, an awful lot of them (if not the majority) WERE the old Lyman press-on GC. I can still remember shooting through sheets of newspaper at various ranges to see if / where any were coming off. Never found any evidence of it. This was with 311291 and 311290, whose gas check shanks were big enough that some of the first Hornady GC would shave lead when they were seated. I had to flare them to use them.

That said, I DO recall some complaints years ago about undersize gas check shanks that let GCs fall off, though I haven't heard that for quite a while now.

But remember, CB's were originally DESIGNED for the gas check to fall off, just like the cotton patch falls off of muzzle loading round balls. If someone has one of the old Ideal molds, this might be what's going on. Easily fixed by any half competent machinist though ...

[maximus]

i dunno imade a little experiment like i use one 9mm shell put a lead bullet (lubed with lee liquid alox) on top of the filled of titegroup brass case , i did not et the bullet just left it on top whit a little opening in the side from wich the flames form the combustion will come out tru., i lighted the powder inside the brass casin, and flames came out tru the little opening afterwards, i touched the lead and burned my finger because the hot alox melted, but mo molten lead anywhere to be found.
even tough i put 7 grains of titegroup on the 9mm cassing.

[maximus]

News Update: I have develope a blister.

[1Shirt]

Dug some out with GC's attached, some that had shed GC's (probably in flight), and dug out some GC' without the projectile that probably shed at time of impact. Lots of variables. Good thread tho!
1Shirt!:coffee:

[XWrench3]

i have always thought that the current gas checks are really only half of what we need. there should be two of them, soldered or welded together back to back. that way, the backwards facing check, would act as a cup to be forced outward against the bore effectively completely sealing the pressure of the burning powder. the crimp on portion would securely attact it to the base of the cast bullet.

[Molly]

i have always thought that the current gas checks are really only half of what we need. there should be two of them, soldered or welded together back to back. that way, the backwards facing check, would act as a cup to be forced outward against the bore effectively completely sealing the pressure of the burning powder. the crimp on portion would securely attact it to the base of the cast bullet.

This elegant theory just doesn't work in practice. It's simple enough to test: seat an upside down gas check half way down the neck and put a drop of super-glue on it before seating the bullet with the regular gas check. Young gas will STILL seep around the doubled gas check and etch the bullet.

There's another way to seal the bore and keep ALL the propellent gas off the bullet, and there's no guessing about it. Just take a small tuft of cotton or dacron about half the size of an ordinary marble, and push it down the neck into the combustion chamber. Then add a pinch of ordinary Cream of Wheat. It only takes about enough to half fill the neck of a 30-06 case. Then seat your bullet.

When you shoot this load, study the target carefully. You will notice that the bullet hole doesn't have the usual dark edges. A control load without the cotton & Cream of Wheat WILl have the usual dark edges on its bullet holes. The reason for this is that the Cream of Wheat load prevents young gas from putting a layer of soot on the bullet. No soot, no black edges to the bullet hole.

Also, no gas impingement on the bullet means there is no need of the gas check in the first place. That's all a gas check was ever designed to handle. In fact, if you read early shooting documents, you will find that the gas check was often referred to as a 'copper patch', equating it to the cloth patches used in BP muzszle loading rifles.

You can load lead bullets as cast to high velocity and never get a trace of leading in your barrel. I've loaded 6.5x55 ammo with MAXIMUM Hornady handbook loads using bullets just as they drop from the mold: No lube, no sizing, no gas check. Accuracy won't win any CBA matches, but you won't lose any deer with it either. You can also load them down to levels suitable for popping tin cans or squirrels.

There's nothing magic about it. The same technique works with ANY rifle. I've gotten the same results with 7.65X54R, 7.65x39, 30-06, 30-40 Krag, 6.5x55 and 30-30 Winchester. This was also written up years ago in the Cast Bullet Association's newsletter, and has since been confirmed by many other shooters. Other shooters report similar results using almost any fine granular fillers like the polyethylene dust used to protect shot in shotgun shells.

The only drawbacks I've found is the slightly reduced accuracy, and the need to be particular about oiling your bore when you are done shooting. These loads don't use any lube, so they can't leave a thin protective layer of grease in the bore like regular cast bullets do. So the bore is susceptable to rusting if you don't oil it at the end of the day.

[geargnasher]

Wow, there's so much I've missed in the old publications. No lube at all, just achieving 100% obturation is all that's needed to stop leading?

I've certainly noticed cleaner targets when using Dacron, and I can increase the velocity of the 311041 unchecked in my 30-30 by at least 200 fps over the "lead point" simply by adding the filler, so I'm convinced the Dacron alone aids obturation significantly, it just never occurred to me to use it with another, compacting filler. I have also noticed that with Dacron, I can go all the way down to just lubing the space above the check and have no leading at very high velocities, and that if I don't I get a shiny-wet bore full of lube that causes flyers every three or four shots and worries me about barrel ringing.

I was just discussing this a day or two ago with another member who was wondering why bore-riders don't lead the lands since there is no lube on the noses. I'm very much in the camp that argues that lube itself functions at least as much as a stop leak as it does a film lubricant, if not more.

I'm also wondering if just a little smidgen of lube on your plain boolits with the dual fillers would improve accuracy?

Gear

[.22-10-45]

Hello, Guys, excellent post! I had two custom nose-pour moulds made up for my .22 Hornet, both identical, except one had g.c. these are flat nose copys of Ideal 22636, made by Fred Leeth, of Pioneer Products. from an alloy of Steriotype softened with soft lead, they weigh in at 55grs. sized .226 & lubed with Lyman Super Moly, which I doctor with a little beeswax & lanolin for firmer consistancy. The gas check version wears Hor. g.c. anealled. my best accuracy load for the plain base is 7.0gr. H4227 . The best accuracy load for the g.c. version is, 7.3gr. H4227. .7gr.! The only advantage I can see for the g.c. if only ACCURACY is the goal, is it's use in a match, to control any leading as may happen, if one fires too fast, as when chasing a condition, etc. Now gaining velocity is whole different matter. Best of luck!

[thegreatdane]

Has anyone done any post shoot detective work? Recovered boolits from a backstop or shot into gel? It would be cool to see what happens. I am gaining info here to start casting for my 308.

Yep. I have a perfect .357 w/ GC intact back home. I recovered it from a backstop. I'll post pictures when I get home to CO.

[Molly]

Hi geargnasher;

Are you any relation to my cousin Toothgnasher? (BG)

>Wow, there's so much I've missed in the old publications. No lube at all, just achieving 100% obturation is all that's needed to stop leading?

It's not exactly easy to do, but that seems to be all it takes. It's a little easier to follow when you understand that leading is caused by the very hot propellent gas etching micro-droplets of lead from the surface of the bullet. These droplets are of course hotter than blazes, and don't have much trouble wetting out the steel of the bore, especially when slammed against the steel with 40 or 50 thousand PSI. They actually solder to the bore - which explains a lot of how bullet lubes work: Greasy metal is a LOT harder to solder to than clean metal. (But lubes do have other functions: Paraffin wax can prevent leading quite well, but gives very poor accuracy.)

>I've certainly noticed cleaner targets when using Dacron, and I can increase the velocity of the 311041 unchecked in my 30-30 by at least 200 fps over the "lead point" simply by adding the filler, so I'm convinced the Dacron alone aids obturation significantly, it just never occurred to me to use it with another, compacting filler. I have also noticed that with Dacron, I can go all the way down to just lubing the space above the check and have no leading at very high velocities, and that if I don't I get a shiny-wet bore full of lube that causes flyers every three or four shots and worries me about barrel ringing.

Most anything that retards the flow of gas around the bullet should help. But granular fillers are the only things I've found to completely prevent the problem. I don't think the pinch of cotton or dacron does a whole lot except to keep the Cream of Wheat from mixing with the gunpowder charge and losing its effect.

>I was just discussing this a day or two ago with another member who was wondering why bore-riders don't lead the lands since there is no lube on the noses.

Actually, I've done a lot of formal research in this area. I've tried everything I could think of that might influence the adhesion of lead to steel. Speed of contact (up to several thousand fps) has no effect, nor does pressure of contact (up to ~ 40,000 psi) nor cleanliness (or otherwise) of the steel. I have never been able to obtain any adhesion of lead to steel under any condition that does not involve some melting of the lead. This was my first clue to the true causes of leading, and the real functions of bullet lubes.

>I'm very much in the camp that argues that lube itself functions at least as much as a stop leak as it does a film lubricant, if not more.

Frankly, I've wondered about this myself, but the waxes that we use for lubes melt into a water-like consistency at such low temperatures that it doesn't seem likely they could serve as a plug - and efforts to add high temperature fibers or particles are consistent disasters to date - although one test I've wanted to try for years is to melt some Alox / Beeswax lube and stir in some Cream of Wheat. This probably wouldn't feed well through a luber-sizer, but a few bullets lubed by hand could be very informative.

>I'm also wondering if just a little smidgen of lube on your plain boolits with the dual fillers would improve accuracy?

One might think so, to judge from a lot of past history and experience with cast bullets. However, my experience has been that while sizing the bullet to reduce the neck diameter and allowing the round to chamber easily causes no problem, any lube added to the bullet invariably results in larger groups and fliers. I have no idea why this is so, but there is no question in my own mind.

[Dannix]

"2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

The hot gasses are not in contact with the base long enough to melt it.

I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.
One thing that needs to be considered is sublimation. I know sublimation is not something most people think about on a daily bases, but one common occurrence that most can personally related to is the dark tint that can form on incandescent lightbulbs as they age. That dark tint is caused from sublimation of the tungsten filament, and it's "reverse" sublimation (sometimes referred to as deposition) onto the cooler glass bulb. No melting is involved.

Is sublimation an issue with leaden bullets and a way barrel leading can form? No clue. But it's certainly a possibility, particularly for undersized non-jacketeds that have hot gas flowing past them.

[felix]

Sublimation is a good word that explains what we have stated here many times before. That is why boolits need to fit to a T. ... felix

[Molly]

Sublimation is a good word that explains what we have stated here many times before. That is why boolits need to fit to a T. ... felix

Sublimation is also a good word for an exceedingly slow process. It is the word used to describe the gradual evaporation of solid ice and snow from your steps over a period of weeks in sub-zero temperatures.

Does anyone really beleive that lead (which is far less volatile than ice and snow) really sublimates at a rate significant enough to be detected during the firing of a cartridge?

To repeat my earlier post above: Leading is caused by microscopic droplets etched from the surface (especialy edges) of a cast bullet, and blasted against the steel bore of the gun. Anyone who believes otherwise is invited to try to get lead to stick to steel under ANY circumstances or conditions that do not involve melting of the lead. I have done some serious research into the matter. Contact speed (up to several thousand feet per second) will not result in lead adhesion to steel. Contact pressure (up to ~ 40,000psi) will not result in lead adhesion to steel. Nothing I have found will result in lead adhesion to steel except melting of the lead, which then solders itself to the steel if it is sufficiently clean. If the steel is dirty or greasy, temperatures must be considerably higher before lead adhesion will occur. (Does this give anyone any hints about how bullet lubes prevent leading?)

[JudgeBAC]

Molly, your theory also explains why lead adheres to the sprue plate of a mould that has not been lubed with bull plate or some other type of lubricant.

[Dannix]

Sublimation is also a good word for an exceedingly slow process. It is the word used to describe the gradual evaporation of solid ice and snow from your steps over a period of weeks in sub-zero temperatures.
I'm not at all attempting to contradict your take on what causes barrel leading, but let me just say your understanding of sublimation is woefully inadequate. I'll stop here, but if it was as you describe, it would make general aviation much easier.

Sorry to ruffle any feathers. I happened to come across this thread, and thought I'd add an additional consideration.

[felix]

Yeah, Molly, it's amazing that sublimation can occur at very cold temperatures. Where does the energy come from to do so? Who says it has to be heat? Cannot it be wave energy? Then, what about 4000F heat? Enough energy there to do a number on a lead compound/alloy? Think about what is going on, please. Research it. You are a smart guy, and a good communicator as well. Let's try and not get hung up on word meanings, but by all means pay attention to concepts. Granted, sublimation might be a word with a very specific meaning which is being misused here. 'Bout like the meaning of the dictionary meaning of SEE versus the way we have been using it. ... felix

[Molly]

Yeah, Molly, it's amazing that sublimation can occur at very cold temperatures. Where does the energy come from to do so? Who says it has to be heat? Cannot it be wave energy? Then, what about 4000F heat? Enough energy there to do a number on a lead compound/alloy? Think about what is going on, please. Research it. You are a smart guy, and a good communicator as well. Let's try and not get hung up on word meanings, but by all means pay attention to concepts. Granted, sublimation might be a word with a very specific meaning which is being misused here. 'Bout like the meaning of the dictionary meaning of SEE versus the way we have been using it. ... felix

You know Felix, I was sincere when I made my post above, but I find I have been mistaken. Sublimation is defined as the transition of a solid to a gas without an intermediate liquid state. The example I was given in school (many MANY years ago) was the sublimation of ice into vapor at sub-freezing temperatures, with the necessary energy coming from wind and winter sunshine. But that's only an example. There is nothing in the definition I was given that requires the transition to occur at low temperatures.

I HATE being ignorant. So I did a web search on lead sublimation, and received a real education. Lead not only sublimates, the process can be sufficiently rapid that it is used for the commmercial production of lead pigments. (Or was used: Lead based paint pigments aren't real popular now.)

I still do not believe that sublimation is at all likely to play a role in barrel leading, but I need to retract my earlier comments, and apologize for them. I also need to render thanks for being corrected. I have no better friend than someone who teaches me. Thank you sir, for the lesson. I am in your debt.

[felix]

Molly, absolutely zero debt about anything, and definitely no apologies needed for learning from others via any kind of media. Effort expended for learning is the minimum payment paid. Learning is a never ending quest one way or another, consciously or otherwise. We ALL are ignorant of facts, and that's saying the least because we are not the Author of any fact. We can only observe a phenomenon and use an evolving language (i.e., math, symbols) to visualize that phenomenon. ... felix

[mold maker]

Too deep for me. I just hate having to remove lead from a gun after the Boolit has left.
It ought to take it's trash with it.

[Dannix]

If I had to go into debt for every time I learned something here, even just from felix, I'd be a broke man.

Sublimation is really a neat phenomenon. If you want to spend a little more time in this realm, you may find triple-points interesting, or look up carburetor icing. (more than one new pilot has had a really bad day from carburetor icing, which is a potential threat even at up to 70F).


It ought to take it's trash with it.
Maybe we could get some legislation passed that will whip those Pb atoms into shape.

[Molly]

Too deep for me. I just hate having to remove lead from a gun after the Boolit has left. It ought to take it's trash with it.

Moldmaker, that particular problem was solved quite a while back. All it takes is a pinch of cereal under the bullet ... and a pinch of cotton to hold the cereal in place and keep it from mixing with the powder. My experience has been with dry Cream of Wheat granules, but others have reported success with Grex, the polyethylene granules used in shotgun shell loads.

There are extensive write-ups elsewhere on the forum if you want more details, but the short version is that it will not only prevent leading, it will also remove every trace of leading you might already have in the bore, and it only takes a few shots to do it. Feel free to PM me if you want.

[largom]

Molly, absolutely zero debt about anything, and definitely no apologies needed for learning from others via any kind of media. Effort expended for learning is the minimum payment paid. Learning is a never ending quest one way or another, consciously or otherwise. We ALL are ignorant of facts, and that's saying the least because we are not the Author of any fact. We can only observe a phenomenon and use an evolving language (i.e., math, symbols) to visualize that phenomenon. ... felix

WOW! What a statement. This should be required reading [and understanding] by everyone.

Larry

[MakeMineA10mm]

WOW! What a statement. This should be required reading [and understanding] by everyone.

Larry

Yeah, he's pretty good! ;-)

Guys -- I'm getting a real education as well, and I thank you. Had no idea I'd start something with so rich of wealth of information over such a simplistic question over the little copper cups that go on SOME of our boolit designs!


At the risk of hi-jacking my own thread (which I think is perfectly legal, actually :grin: ), I'm curious how the old trick of wrapping bullets with teflon plumber's tape fits in with this theory of escaping leading, especially as explained by Molly? (I'm theorizing that it would be an alternative to fillers in the application Molly has described, as the teflon tape would protect the lead from the hot gasses??)

(Yet another twist to the quest...)

:hijack:

[ReloaderFred]

I don't know about the theory of using teflon tape, but I know a couple of people who tried it and soon abandoned it. For whatever reason, they got much worse leading than with untreated bullets.

Hope this helps.

Fred

[Molly]

At the risk of hi-jacking my own thread (which I think is perfectly legal, actually :grin: ), I'm curious how the old trick of wrapping bullets with teflon plumber's tape fits in with this theory of escaping leading, especially as explained by Molly? (I'm theorizing that it would be an alternative to fillers in the application Molly has described, as the teflon tape would protect the lead from the hot gasses??)
(Yet another twist to the quest...) :hijack:

FWIW, I tried the teflon tape idea a very long time ago, but never had any success with it. I'm not sure why, but PERHAPS it was because the tape is so fragile, and would be blown away by early gas. BTW, don't bother to try patching with aluminum foil either. That stuff is THIN, and it takes a lot of wraps to build bullet diameter. And when you've done all that, it doesn't shoot worth a darn anyhow.

In the context of eleminating leading, it is noteworthy that PAPER patched bullets don't require a gas check, even when loaded to magnum velocities. Properly applied and loaded, they will shoot very well in rounds like the 300 magnums without producing a trace of leading. The explanation (it seems to me) is that paper does not melt, nor does the flame penetrate it to reach the bullet. It is rather surprising at first examination that the paper isn't instantly consumed by the propellent gas, but it isn't. So the gas never gets a chance to etch the bullet, and leading simply doesn't occur.

HTH

[MakeMineA10mm]

Yes, that helps reference the teflon tape. Sounds like more research might be useful. I recall the article I read about (maybe 20 years ago), said something like having to wrap it according to the direction of twist of the rifling, just as with paper-patched boolits.

As far as paper-patched goes, I had a friend who was an engineer at a paper-label manufacturing plant, and he told me that paper is a very good metal polisher, as all the drums on the machines that ran the paper through became polished like chrome after they ran for a couple months. Made us conjecture whether you'd ever have to clean a barrel fired with paper-patched bullets! [smilie=1:

One last curiosity to set your minds to: It is interesting that the paper-patch is so successful, but when half-jacket bullets (which are really just extra-long gas-checks) are pushed too hard, they lead. I've seen this blamed on the extremely soft, pure-lead core, which just barely sets against the barrel at the joint of core and "jacket" with the writer saying that the nose slumped under too hot a load and put even more lead in contact with the bore, which resulted in leading. BUT you all have very accurately explained how it's gas-action, not lead "rubbing" (for lack of a better word... So, what's going on with those half-jackets??

[Molly]

... One last curiosity to set your minds to: It is interesting that the paper-patch is so successful, but when half-jacket bullets (which are really just extra-long gas-checks) are pushed too hard, they lead. I've seen this blamed on the extremely soft, pure-lead core, which just barely sets against the barrel at the joint of core and "jacket" with the writer saying that the nose slumped under too hot a load and put even more lead in contact with the bore, which resulted in leading. BUT you all have very accurately explained how it's gas-action, not lead "rubbing" (for lack of a better word... So, what's going on with those half-jackets??

Well, I'll take a crack at it. Without examining the exact loads and results, I can speculate that the slumping with hot loads (which DOES occur) brings lead out to the surface of the bore. The half jacket is indeed a 'super gas check', but gas leaks around gas checks all the time. I can detail the process for you, but not at this time. The pertinent fact is that they DO leak gas past the base of the bullet. As pressures go up, so does the leakage. Not only that, but hotter loads actually wear away the side of the land engraving, producing an engraving that is wider than the lands that made them. The extra width is simply a sort of drainage tube that channels propellant gas along the side of the bullet, up to the front. If the lead has slumped, it simply becomes feed for a molten metallic spray of lead onto the bore, with substantial leading occurring.

Paper patching, on the other hand, generally involves bullets considerably harder than pure lead, and much less succeptable to slumping. Also, the paper does not wear like hard lead and even copper will do, and the gas leakage is thus much reduced.

Some folks have argued with me about this engraving enlargement, but all you have to do is recover a few high-power bullets from the backstop and compare the width of their rifling to the rifling of a bullet you used to slug the bore. It's easy to do, and the different groove widths will leave no doubt in your mind.

[MakeMineA10mm]

Great answer, well explained. Understand it the way you described it, perfectly. Thanks!!

[thegreatdane]

http://i25.photobucket.com/albums/c66/drobberson/IMG_2011_01_03_4335.jpg

The picture I promised.

[TXGunNut]

OK, just got my first GC mould and read this whole thread. Wow! All the physics and metallurgy was fascinating so I dumbed it down enough so that I could understand it; please correct me if I'm wrong.
1. GC boolits perform almost as well as j-word bullets in the bore.
2. GC boolits perform as well as cast boolits in the boar.
3. GC boolits get thru the bore faster and cleaner and hit harder just in case the boar is big and mean(er).

All kidding aside, you folks are awesome! I've hesitated to get into GC's but they're on my project list, might as well start thinking about it. I think I'm ready to give it a try...very soon!

[Old Kid]

I'm new here, although I've been reading posts for some time. I'm casting various calibers of boolits and have been experimenting with gas checks. From what I've read here it seems that I can use softer alloy when I'm using a gas check and still not have to worry about leading. Is that the case?

Old Kid

[Molly]

Hi Old Kid,

In my experience, the improved performance from gas checks is because they are much higher in melting point than lead alloys, and hardness doesn't seem to have much to do with it. As the round is fired, there is some gas leakage along the base and sides of the bullet. These gases are very hot, and will etch a very fine spray of molten lead off of the bullet base edges and the sides of the bullet. This molten lead is then soldered to the sides of the bore as leading when the bullet catches up and passes the spray. Gas checks reduce this because they don't melt or etch nearly as easily as lead. But they're not perfect, because as you increase you load, the gas can and will etch more and more droplets off of the side of the bullet, and you will eventually get leading again.

There IS a simple, easy and inexpensive way to prevent gas leakage entirely, and allow you to shoot cast bullets with jacketed bullet loads. It works with all loads, from power levels suitable for everything from mice to moose. Just place a little bit of Cream of Wheat ("COW") beneath the bullet. This will let you shoot cast bullets just as they drop from the mold: No gas check and no lube. And if your throat is big enough, you can even shoot them with no sizing. But this trick does have a liability: For some reason, it seldom gives high precision accuracy. You won't lose a deer because of it, but you could lose a groundhog that's way over yonder. A 4 to 6 inch group at 200 yards is about what I'd expect from maximum loads, though some guns do quite a bit better, and some do worse. You'll just have to try it and see what kind of accuracy you get with your loads, and decide if it's acceptable for you. As with anything new, start low and work up gradually, changing ONLY one thing at a time. This has been gone over in some detail in previous postings. Do a search for 'COW loads" or "Cream of Wheat".

[Dannix]

But this trick does have a liability: For some reason, it seldom gives high precision accuracy.
Didn't realize that. Thanks for posting Molly!

[.357MAN]

I know this is an old thread but I joined CB so I could post my opinion.
Even in my brief experience with cast bullets I feel I have learned quite a bit thanks to CB.
I can't help feeling that lots are over thinking this, me included. According to everything that's been said:
(1) Gas check are to either: Shield the bullet in one way or another from hot gas through gas cutting (<more popular view), or to give the bullet a higher shearing strength.
(2) Leading is caused by poor bullet fit, thus vaporizing lead by gas blowby along the bullets shank and depositing lead along the barrel, then the bullet ironing it onto the barrel surface.
(3) Lube is to either: Blocks gas blowby ( <more popular view), or lube the bullet shank as to reduce friction.

I conducted some unprofessional tests to see whether my alloy was up to my standards of presser I wanted to run them at. I started with an unknown lead alloy so I got a Lee's hardness tester ( It killed me to spend the money, but I really wanted to now my alloy's BHN ) . It gave consistent reading to within +1.5- BHN. My alloy was within 1 BHN of pure lead, but I thought "what the heck it'll go down the barrel" so onto the load development part. To make sure the bullets weren't striping in the rifling I shot one out of each test lot into milk jugs ( yeah, low tech. ) then retrieved the bullet and checked the riffling engravings. Needless to say the bullets started to strip at about the fourth lot ( 38 Spl. 158 Gr. TL PB bullet with LLA, 3.4 Gr. Trail Boss, guessing around 12,500 PSI ) of the planned to be eight lots. So I got taught about sheering strength fairly fast. After that I richened the alloy with Lino type to make a BNH of 10.4 +1- , and now with same bullet and lube using 4 gr. of TB and LLA I am getting good groups at 25 yards.

So going along with others I think the gas checks are to aid in shearing strength of the cast bullet alone. Before you members that don't believe this start to hammer me, think about it. Imagine a bullet like mine pushing 13,700 PSI ( Max for TB in my setup ) the bullet would be totally striping in the rifling. Why? Because the leads max shearing strength has been exceeded, so it strips the rifling, causing leading. Now, imagine a bullet similar to mine but with a GC base with a GC on it. As the bullet is starting into the rifling it starts to strip ( keep in mind the bullet's whole shank doesn't fully strip the rifling until the bullets is completely engaged by the rifling, cause it's the rifling twisting that strips the bullet from the rifling ) from the front to the back (As the bullets soft alloy can't start the bullet twisting ) once the GC gets to the rifling the GC is crushed into the shape of the rifling. Which in doing squeezes the bullet to conform to the new shape of the GC. The GC would look more like a socket wrench hex shape ( if there is 6 rifling groves, if 8 groves then octagon shape and so on ) than a cylinder shape. Now the GC acts just like a wrench to turn the bullet ( now, since the bullet just started into the rifling the bullet is not fully striped of its groves in the rifling) keeping the last little bit of the bullet closest to the GC from striping and letting gas melt the shank, causing leading.

Now bear with me for a little longer, as I am not done.

Some members have in deep detail told about the way leading is formed in the barrel due to gas cutting.
But I think It's more than just gas cutting.
Imagine a .358" PB bullet traveling down a 6" barrel lets say at 1109 FPS with 23,900 CUP (max for HP-38 in .357 MAG.) behind it, and the barrel has a .001" restriction in the first one inch then goes back to normal diameter. Well now there is a bullet that is not making a perfect bore tight seal in the barrel at the most critical point of pressure. What would happen? Hmm... lets think about it. Maybe the gas would blow past the bullets shank? Yes. Then what? The bullet will leave leading in the barrel. Well yeah! duuuuu! Why dose it lead?
Most think the hot gases have a blow torch effect on the bullets shank eating away the alloy at an almost microscopic level and this then gets deposited onto the barrel further down. Other opinions include chatter down the barrel causing leading (the latter is not really in this thread but I have heard it on others ) and a few others that I can't remember.
From what I hear gas cutting sounds the best and most sensible. But this thread got me to brain storming some ideas. When the gas blows by the bullets shank I think more than one thing happens from blowby.
(1) All the lube in the area gets air blasted off the lead and the barrel.
(2) The lead bullets shank that's exposed to gas gets heated, no one knows how much, but it gets hot.
(3) The gun barrel exposed gets hot, like I said before, no one knows how hot.
I think the three together make the perfect environment to solder the hot lead right to the barrel from the bullet's shank.
This would explain why most leading is specific to the area of the bullet that is under size, and why it looks like smudges and not small ironed on beads / splatter (although some could look like this, when I got leading it was smudging ).

Ending with the lube subject, I think its effect is to seal off hot gasses from escaping around the bullet's shank thus welding the exposed lead to the exposed barrel surfaces. That's why so many members have good successes with high presser greases, they are always thick and gummy in wide temperature ranges, and they seal the imperfections in-between the bullet and the barrel better than other lube.

Sorry It's so long, but I couldn't hold it in, I had to put my 2 cents in.

.357MAN

[Molly]

Hi .357MAN,

>I know this is an old thread but I joined CB so I could post my opinion. Even in my brief experience with cast bullets I feel I have learned quite a bit thanks to CB.

Yeah, this is a great site where almost anyone can learn a new trick or two. For example, I had never considered the rifling making a sort of toothed gear out of the gas check, and thus assisting in bullet rotation. Could be. There's no rule that says something can't work in several different ways. But you've got to be careful not to overlook contrary data either. For example, Col. Harrison showed rather convincingly that even pure lead can't be stripped by rotational stress alone.

>(3) Lube is to either: Blocks gas blowby ( <more popular view), or lube the bullet shank as to reduce friction.

Lube may have some slight gas blocking or friction reduction effect, but that's probably not it's major function. In fact, lube isn't even necessary for decent accuracy. Air rifles give superb accuracy from pure lead at over 1000 fps without a trace of our greasy lubes. And even using our cast bullets, you can eliminate the lube (and the gas check) and get decent accuracy with CoW loads.

>so I got a Lee's hardness tester

Did you consider the pencil hardness test method? Works great, costs pennies. There's a thread on it here somewhere. Do a search.

>Needless to say the bullets started to strip at about the fourth lot ... After that I richened the alloy with Lino type to make a BNH of 10.4 +1- , and now with same bullet and lube using 4 gr. of TB and LLA I am getting good groups at 25 yards.

I've seen bullets with engraving noticeably wider than the lands, but it wasn't from rotational stripping. It was from abrasion against the sides of the lands. I HAVE seen shear stripping in a barrel with VERY shallow rifling. It was an interesting experience, because you could look down the barrel and see thin strings of alloy all over the place. The shallow rifling apparently acted a lot like a potato peeler, and left the peelings all over the bore.

>So going along with others I think the gas checks are to aid in shearing strength of the cast bullet alone. Before you members that don't believe this start to hammer me, think about it.

Let me recommend that you review Col. Harrison's research on this before you set that opinion in concrete. You can get a copy of his report from the NRA for free.

>Now the GC acts just like a wrench to turn the bullet (now, since the bullet just started into the rifling the bullet is not fully striped of its groves in the rifling) keeping the last little bit of the bullet closest to the GC from striping and letting gas melt the shank, causing leading.

Like I said, the wrench theory is interesting, but the base / shank of the cast bullet simply doesn't melt in bulk with any reasonable load. Proof of this can be picked up at any range, where it is easily seen even jacketed loads at notably higher pressures and temperatures of even jacketed loads isn't severe enough to do the job.

Now bear with me for a little longer, as I am not done.

>From what I hear gas cutting sounds the best and most sensible. But this thread got me to brain storming some ideas. When the gas blows by the bullets shank I think more than one thing happens from blowby.
(1) All the lube in the area gets air blasted off the lead and the barrel.

Nope: Cast bullet recovered and examined show plenty of lube still in the grooves after shooting.

>(2) The lead bullets shank that's exposed to gas gets heated, no one knows how much, but it gets hot.
(3) The gun barrel exposed gets hot, like I said before, no one knows how hot.
I think the three together make the perfect environment to solder the hot lead right to the barrel from the bullet's shank.
This would explain why most leading is specific to the area of the bullet that is under size, and why it looks like smudges and not small ironed on beads / splatter (although some could look like this, when I got leading it was smudging).

>Ending with the lube subject, I think its effect is to seal off hot gasses from escaping around the bullet's shank thus welding the exposed lead to the exposed barrel surfaces. That's why so many members have good successes with high presser greases, they are always thick and gummy in wide temperature ranges, and they seal the imperfections in-between the bullet and the barrel better than other lube.

The microscopic droplets etched off by gas blowby are melted as part of the etching process. They don't have much opportunity to cool as they are carried into the bore by the hot gas, so when the bullet slams past, they are still soft (if not still actually molten) and easily smeared by passage of the bullet.

And while lube probably does have some sealing function, I believe the evidence shows that their primary function is to contaminate the bore and prevent soldering by the etched alloy droplets. Think of trying to solder dirty steel or copper and you will understand. Then try this: Load up a bore mop with lube and scrub the bore before each to be sure every surface is coated. You will find that leading can and will still occur with hot loads, despite all the sealing function you can add to the bore. The reason is this: The etching action of blowby doesn't have any problem melting lube and spraying it into the bore ahead of the bullet, just as it does the lead. This molten lube is quite low in viscosity, and wets out the bore (IE contaminates it) and prevents leading because its surface tension is lower than the surface tension of the melted lead etchings. The molten lube thus preferentially wets the steel, and prevents wetting by the molten lead alloy. But with increasingly more powerful loads, the higher temperature of the gases result in higher temperature and lower surface tension of the etchings. Higher temperatures also promote decomposition of the lube, which is thus less able to wet the steel bore. Remember, the flame temperatures exceed the melting point of steel. Sooner or later, the increasing wetting ability of the hotter allow etching overcomes the decreasing ability of the lube to wet and contaminate the bore. The result is leading.

>Sorry It's so long, but I couldn't hold it in, I had to put my 2 cents in.

Put in ten cents worth. It's always good to hear from someone who is interested enough to actually run tests and think about what the results could mean. You're welcome here indeed.

[.357MAN]

Hi Molly,

I am sorry to say I have never read Col. Harrison book, but I hope to acquire a copy in the future. I am certain it will be enlightening to say the least.
Yeah, the more I think about it, the more it makes sense the rifling would not fully strip the bullet in normal rifling. But it would still make wider engraving such as you experienced, which in theory would cause leading by gas blowby.

I completely agree with the CoW, it makes perfect sense( although I did not mention it in my first post ). From what I can grasp of CoW is that it fills the role of the lube ( makes sure gas doesn't blowby the shank / side ). Using only CoW also suggest that the lube has little if any lubricating effect on the two surfaces. That's why I say lube is only to seal the gas from leaking around the bullet.

I agree with you that it's abrasion against the sides of the lands. I think I used "striping" wrongly to convey what I meant. But it is the shearing strength of the alloy that resists the abrasion / cutting and turn's the bullet. That's why GC help so much with softer alloys, they add shearing strength to the bullet.

"Shank" Again a bad usage by me,:oops: I meant the sides of the bullet. When there is not a tight seal the shank / side are exposed to the hot rushing gases, thus blowing lube away and melting the shank / side and smudging lead on that nice clean bare spot in the barrel.

Yes! bullets have still have lube on them even after going through 6 1Gal. jugs of water.
I am saying at the point of the gas leek ( not the entire bullet surface ) it is folly to say that the lead is melted and blasted away and not the lube. Most lubes flame point is at 250 F. +100- degrees, yet lead melts at 600 F. to 700 F. .

Yes, there could be micro droplets from blowby but its insignificant. But how do you explain after one to three shots that there is a large smear in a specific area? Another thought is, if indeed lead was melted by gas ( <I agree with this) ( not this >) then blown forward of the bullet, then the bullet ironing it on, causing leading. If so, then the lube forward of the bullet would protect the barrel, and the bullet would then scrape the lead off ( according to you, this is one of the main effects of lube ) and we would never have leading in light loads even with soft or under sized bullets.

I have soldered, and I have welded, and I know what you mean. But then why is there leading with lube more than CoW? Because CoW is thicker and so a better sealer than lube, thus no gas could pass the bullet even with a bullet that has small openings which would otherwise let gas leak destroying lube and soldering lead to the barrel.

As far as swabbing the bore with lube, of course it wouldn't help. Lube has to be behind the bullet so the pressure would force the lube into the imperfections, thus making a tight seal.

If it's true that lubes primary function is to contaminate the bore and prevent soldering by the etched alloy droplets, then why would I get leading with extremely low pressure loads that would not exceed the lubes abilities to wet the barrel?
Because it's not wetting the barrel, it is sealing the imperfection to stop gas from melting the shank / side to the barrel. That is why I got leading. The imperfections on the bullets were to large for the lube to seal, thus gas blowby blew the lube out of the area and heated the two surfaces which then smeared lead, leaving leading.

I hope I have explained in a better manner than my first post. Thank you for welcoming me, and it is appreciated greatly.

P.S. sorry I can't quote you, as I am new and not a computer wiz.

.357 MAN

[johnnybar]

"2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

The hot gasses are not in contact with the base long enough to melt it.

I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.

Did your torch also provide a pressure differential of 10,000 to 30,000 psi across the area being torched? I'm being a bit sarcastic...obviously it did not. Pressure is a major force to bring under control in reloading naked slugs. Look at what it and temp can do to a little graphite....diamonds.

[johnnybar]

An example of extreme pressure to keep the think tank going here:
Here we have pressure acting on lead and steel plate. Insert enough pressure into the equation and lead can literally splash steel like soft butter. In our leading challenge, we have high pressure gasses vs. lead, GC and lube. Lots to think about....
54390

[fcvan]

For decades, I only used gas checks when I launched beyond 1200 fps. I would buy 1000 checks and they lasted a long, long time. After using the last of my checks purchased at 10 bucks a thou I was shocked to see what they want for checks these days! Heck, I used to use checks as under and over shot wads for snakeshot rounds which used them twice as fast. Then I bought some CheckMaker dies, some regular and some plain based CheckMakers. I'm putting gas checks on boolits that are under 1200fps and don't really need them. Checks are like spinners on a 67 Chevy. The tires don't roll any better but they look cool :)

Ok, back to seriousness. Plain based checks on non magnum loads can be a crutch for folks who haven't found the fit, lube, and powder combo and are still experiencing leading. I have a buddy who prefers to shoot jackets because he's worried about leading and would rather not risk it. He will shoot gas checked boolits so it gives him piece of mind. I like reloading which for me now includes making my own checks in addition to pouring my own. My next endeavor will be making my own black powder! Frank

[Ray1946]

Hello all! Yes, I have sat here and read all 6 pages of this very informative thread. WOW! I think my brains ready to EXPLODE! Since everyone has had there say, I think it might be a good idea for me to include mine.

I started reloading cast bullets in a Mosin-Nagant in 1974. Back then I was getting Norma brass for $.20 a pop. I bought some Lee molds and began casting some pretty nice boolits. These came out of the mold .3118 and so I shot them unsized, but seated a Hornady gas-check. The groove in that rifle was a solid .312, so I was slightly on the low side of the groove diameter. Some of the beginning loads back then were more than maximum by today's standards. I got great results if I didn';t go over about 1400-1500 fps with most of the fast rifle powders;4227,2400 RL7. I fooled with this for 3 or 4 years while reloading for a .222 with jacketed bullets.

Slide on down to 1981 and becoming interested in 100yd. highpower. In my area there were not a lot of really close 2,3, and 600 yd. ranges, so the big deal at that time was shooting reduced to 100 yds. Looking around at something that might be competive and AFFORDABLE, I opted for a 96/11 Schmidt-Rubin. This is one incredable rifle! Mine, along with every other one I have ever seen has a near perfect barrel that is a whopping 30.7 inches long; right at 36in. between the front and rear sights. I epoxy-bedded that action, bought a Williams micrometer sight for the rear and a Lyman globe for the front and we are off to the races. My most accurate boolit was the Lee180309 at about 1650-1675fps, the lube was Alox 50-50 and I managed several .3 and under 50yd groups from a rest. I later bought an NEI 195311. This is a really beautiful bullet and would perform great using RL7 at about 1750 fps.

The whole thing about what I learned was that in High-power, you have to shoot from 50 to 90 rnds WITHOUT cleaning,so if something breaks down, you are going to be all over the target for a whole lot of rounds. The groove in the old Swiss was .3094, so I sized my boolits at .3105 and this seemed to work very well. At the time I was using straight Linotype and although this made a wonderfully HARD boolit, the boolit also had a lower melting point than say No.2 alloy. I think the melting point of the alloy has a significant effect on its plasticity as it absorbs impact and heat for a micro-second of time. With Linotype, once a certain pressure/TEMPERATURE threshold is reached; you get leading, I think mainly because of the lower melting point of the alloy.

Another factor I think adds to good accuracy and consistency is the lubricant. I think lube is not just a lubricant, but also a COOLANT. I shot several cast bullets lubed with a moly dry-lube and gas-checks, but NO lube in the grooves and they leaded terribly. The same dry-lubed boolits with lube in the grooves performed flawlessly...........................

[morton45]

It's been very informative to read the various theories & opinions on the subject. I suppose that through my experience lead hardness definitely had a role to play. For example soft lead Hollow base wadcutters are great in my 6" 586 S&W at 900fps, however in my 18" Browning M92 I can't load them much higher or I will get leading or worse they will separate. I believe the seal between projectile & bore is very good at this lower velocity & pressure. However when I try for more speed I am in effect deforming the projectile due to higher pressure & more powerful ignition.
I believe after a point the gasses burning the bottom corners or edges of the projectile & each subsequent shot will smear the previous deposit along the bore.
The faster the projectile the harder the alloy until you need a gas check. One shooter suggested they had shot thousands of US Military issue jacketed rounds where the base of soft lead was exposed & no leading had occured in this instance. Well I believe that's because the jacket wraps around the bases edges or corners. This is the weak point. I have found when melting anything be it wax, lead or even cutting with the Oxy torch, it's much easier on a corner to start the melt than in the centre, although that can be done with greater heat.
Lube is, as Ray above suggests both lubricant & Coolant. The same principles are at work in your average internal combustion engine. The oil lubricates the moving parts but the oil also plays a critical role in carrying the heat across for the cooling system to radiate externally.

Just my thoughts, Cast bullets are fun & challenging. I'm sure gonna research these COW loads. Thanks to all.

[billurbank]

Some years ago ML McPhearson wrote an article on building a boolit trap that does not deform the boolit. He used a sheet of plywood cut in one foot by eight foot strips to mke a box eight foot long. Fill the box with fine saw dust from the saw mill and saturate the sawdust with hydraulic oil. I built this and can tell you that the results are better than hoped for.
Because I can see uncorrupted proof of the changes I make in my experiments, I believe it keeps me on a narrower path. I have satisfied myself about lubes, bore alignment, boolit/rifling, and terminal performance as well.
I plan to compare the three foot water column trap to the sawdust.
The point is, speculation can be moved forward

[LeSellers]

As a newby, I have no opinion, much less any helpful information on gas checks. I do have a question, however.

Whatever function a gas check has, is it duplicated when a bullet (factory) or boolit (hand cast) is copper plated?

If we assume that a gas check keeps barrel leading to a minimum, would a very thin layer of copper plated onto a similar boolit keep the barrel fouling to the same kind of level?

Le

[psychicrhino]

Questions answered I didnt know I had

[garand41]

About the black powder. If you would shoot a muzzle loader at nite, you will find that a lot of the powder is expelled, on fire, from the muzzle. Black powder does burn down the barrel, it does not explode!

[giericd]

i know this is an old thread, but some of us are new to the site and just comming across it- so by cointiuing to add to it might help some of us new guys. im new to casting and had some thoughts/questions about gas checks. i've played around with heating a lot of metals/aloys. I've done a bit of blacksmithing so i understand hardness of metals vs. hardness when heated. there is no way you can take a tortch to a cast bullet and see how long it takes to melt and compare that to what happens to the metal under the same temp under thousands of PSI! this much i know. my question is has anyone experienced and damage to their bore (sctatches/scrapes/groves) due to the gas check rubbing the walls? Also a safety question- if it seperates from the bullet after leaving the barrel the bullet heads in the direction you aimed but what happens to the gas check? sorta like throwing a CD, that sucker could exit the barrel, take a 90 degree turn to the right, then back left who knows but it could end up hundreds of yards off course to the right or left where you didn't intend for a projectile to go. As far as seal goes i highly doubt it, at .005" how much seal are you going to really get. any seal you would get would be due to the diameter of the bullet like .224 in a .223 rifle or a .401 bullet in a .40S&W ya might get a little more seal with cast due to it being a softer metal and the midsection of the bullet expanding (flexing) slightly when the round is fired. as the pressure of the round going off hits the base of the bullet it starts moving forward before the fromt of the bullet by a fraction of a second, for that breif time the lead in the base that moved forward would have made the mid section expand slightly creating more of a seal. so my theory would have to come down to the gaschecks only purpose is to prevent the base of the bullet from deforming/melting under heat and pressure causing leading and destroying accuracy, and since it is made of a more heat resistant material than lead and equally spreads out the pressure the base of the bullet is subjected to it allows for more powerful loads and to reach faster bullet speads than lead alone would allow. just my thoughts. what do you guys think?

[blackangus]

what filler for a 30-30, if my bullets are not rebated?

[kolob10]

Great compendium of the wealth of knowledge and experience on this site. Thanks! I would only add that many years ago a was at an insurance underwriter test facility and witnessed a demonstration explosion of some corn meal dust. The chamber in which the explosion originated was a bunker dug into the side of the hill with one side exposed but covered with a "plastic curtain" that appeared to be an industrial shower curtain. The bunker was designed to direct the force of the blast (path of least resistance) toward those who watched the blast through the plastic curtain. The onlookers were placed behind a transparent blast shield 100 yards distant.

After the blast, I was curious as to why the "plastic curtain" was placed in front of the bunker. The chief Engineer explained that it was used to absorb the heat energy coming from the blast to make the demonstration more viewer friendly and prevent grass fires. Indeed I felt the blast but very little heat energy reached the viewers.

After I returned home I wondered if I could do the same thing for the PB cast bullets I was shooting in my 357 mag to reduce leading. I knew nothing of matching the sized bullet to the groove diameter at the time as I purchased all my cast bullets locally.

I did some research and decided to use styrofoam. I sharpened a 357 case neck (used as a cutter) and proceeded to cut some disk out of a styrofoam egg carton. I placed the syrofoam disc on the top of each powder charge prior to seating the cast boolit. It worked pretty well to my surprise.

Later I learned that NASA placed an "ablator" or head absorbing shield on spacecraft to reduce heat damage. I'm a gas check guy myself on everything except my 44 Special loads. Old thread I know but great info.

[HogsTooth]

"2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

The hot gasses are not in contact with the base long enough to melt it.

I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.

YESSSS..but did you apply the heat at 30,000 PSI?

[popper]

Read this awhile back, just thought I'd add some test data. I shot 30/30 & 308 full house loads, GCd with real runny veggie oil. Boolits cast with #2, 165 gr., Hornadys Non annealed GC, just dipped the base into veggie oil. 311 for the 20/30, 310 for the 308. No leading at all, 40F & 90 F. The oil can't seal the bore. When pulling goofs, GC come off in the neck & un annealed tend to mess with neck tension. Pulling PCd boolits, the un annealed GC still tends to stay in the neck. Annealing tends to increase accuracy, but BHN is much lower. I conclude that GC actually do some sealing, lube is a friction reducer. I've been able to push unchecked to 70% of checked speed with accuracy. I need to push the unGCd harder to see wh e the alloy fails, vs when the GCd combo fails.

[AABEN]

I use gas check in my 44Mag when I want to use a softer bullets so they can expand more that way no lead in barrel and the bullet shoots accurate.

[bld451]

Here is a photo of an NOE 153 HTC through my blackout at 1700 fps. 50/50 ww/pure with 2% tin, air cooled. 16.5 grs 296 IIRC. Crimped where there is no crimp groove on the bullet. Notice the eroded lead pretty far up the lands and around the circumference of the crimp groove. 261777 there is actually a leading edge issue in this case. I'm going to try PB checks.

This one is a MP 311-235 shot at 1050 with AA1680. Some erosion at the base. Not as bad as the 153 but still there. Didn't have any lead fouling or buildup, so seems ok as is...261779

[popper]

Actually the sub is worse than the super. Base is below the shoulder! It will cut the 'corners'. I see no evidence of problems in the crimp groove, just 'trash'.

[bld451]

It looks like the cutting along the leading edge of the super's rifling got all the way out to the front of the bullet. The pockets at the front of the crimp show there seems to be quite a bit of pressure getting to the front of the crimp groove. I have some PB checks I need to seat and will have some direct comparison photos hopefully soon. I'm getting easy cleanup and no noticeable leading with either of these, but am hoping I can tighten up the groups a little (or a lot...) seems the cutting is not evenly distributed around the base, so all that sorting for base defects is for naught. Funny, I started this as a cheaper alternative so I could shoot more. Well, I am shooting some but as usual, it gets a bit in the weeds trying to achieve "better".

The sub bases are definitely seated well into the case. Enough that I am hesitant to check them for fear of one coming off in a case. The supers are right at the end of the neck. There might be some exposed right at the radius of the neck/shoulder but I'm certain a check would be almost totally retained by neck tension. We'll see.

Thanks for the feedback.

[popper]

I shoot a 145 PB faster (H110) in BO no problem and accurate. I use PC and HT, no leading, no tin. Never recovered any. Soft alloy can allow wide groove and gas cutting but yours look reasonable. 1680 is pretty slow (and dirty!) so possible the sub is seeing cutting when leaving the crown. Tune for accuracy and shoot em. Note: I've never gotten good results in rifle with HiTek. Pistol is fine. Basically changed back to PC as it is more reliable for me.
261797 Un'grouped' were chronied shots.

[bld451]

I shoot a 145 PB faster (H110) in BO no problem and accurate. I use PC and HT, no leading, no tin. Never recovered any. Soft alloy can allow wide groove and gas cutting but yours look reasonable. 1680 is pretty slow (and dirty!) so possible the sub is seeing cutting when leaving the crown. Tune for accuracy and shoot em. Note: I've never gotten good results in rifle with HiTek. Pistol is fine. Basically changed back to PC as it is more reliable for me.
261797 Un'grouped' were chronied shots.

I did notice some unburned powder and slightly dirtier cases with the 1680, but the 225 subs don't reliably lock back the bolt with 4227, h4198 or others I have tried. 1680 is reliable that way. I'm using 296 for the 153 supers. I have done a little testing of limits with 296 and that 153, and it looks ok up to about 1850 or so. I see around 1940 fps on your target. What length barrel are you using?

[popper]

18" 1:10 carbine. Actually ran them in 10" 1:8 pistol but it's a lot to handle. 1680 & cfe blk are dirty. Pistol powder works good for subs but won't cycle action. H110 & W296 are same stuff. I've pushed the PB to 2150, no leading but HARD alloy.

[bld451]

So... first step complete. Punched .437 dia. Discs and formed them with a .312 die.261816

Seated base first, and they are staying put. Can't get them off with a fingernail..... enough to load now.261817

Seems like I hear everything from ]"they're the best thing ever" to " don't waste your time". Time to find out.

[bld451]

261818

Ha... maybe I should have put this check on a different bullet.....

[Watchman 426]

Well, I'm as confused as a termite in a yo-yo! I am thinking of casting .308 for a bolt action 30.06. I would guess that I need a gas check.?.