Myths of the gas check

[bhp9]

One of the great myths about using gas checks is that they prevent leading. Well although it is true that a very small amount of leading can come from the base of the bullet, about 98 per cent or more of leading comes from undersize bullets which let the gas escape around the sides of the bullet, melting the sides of the bullet which in turn can cause some really severe leading.

Years ago I had a .44 magnum pistol that leaded like heck and gas checks did absolutely nothing to stop the leading. Even using pure linotype did not stop the leading either. The problem was one of an under size bullet and because the mold would not throw a larger size bullet I had two choices. Use a slower burning power and more of it to obdurate the bullet so that it filled the bore or go to a softer bullet (much, much softer) and keep on using a small amount of fast burning power that I was using for low velocity mid range loads. The soft bullet was able to obdurate with small amount of power and still seal off the chambers and bore.

So if gas checks do not stop leading then why do I use them, because in rifles, not pistols, I have always got much more consistently smaller groups when using gas checks. The gas check prevents the bullets base from being distorted by the hot burning gases. Once the base of the bullet is distorted you can forget consistent accuracy. This base distortion is due to the much higher velocity that I push my cast bullets in rifles to as compared to pistols ( between 1,700 and 1.900 fps. in my rifles) I always seat the bullet within the case neck to prevent the gas check from coming off as the bullet exists the cartridge case and it also prevents any gas cutting of the sides of the bullet. When the bullet is seated down into the powder charge the gas check will only protect the base of the bullet from being distorted by hot gases, not the sides of the bullet.

I generally like to keep my cast rifle bullets up to around 1800 to 1900 fps because when they are loaded down to move slower the wind just plays to much havoc with the accuracy.

I do not use gas checks in pistols as most of the pistols I load for are not the magnum hunting type pistols but standard velocity military pistol calibers.

[Ricochet]

Another option when the boolit is slightly undersized is to seat the gas check in a properly sized sizing die. At least the check on the base will seal better.

[pps]

I can't say much about the gas checks, but I can attest to the fact that under sized bullets will severely lead the barrel. Here is a pic after 100 rounds of 158gr Hornady swagged lead.http://i94.photobucket.com/albums/l96/pps_2006/leading.jpg[smilie=b:

158gr over 3.4gr bullseye in 38 cases...chrono at 850fps

This occurred because on my first venture into handloading, I failed to sufficiently expand the cases before seating. One of the bullets I pulled measured .356...compared to .358 on the ones in the box. Since belling the cases a bit more, and a dose of LLA there's no more leading.

[PatMarlin]

THat is a COOL photo!... :Fire:

[carpetman]

I have serious doubts that any part of a bullet melts in the barrel---just aint there long enough.

[pps]

I have serious doubts that any part of a bullet melts in the barrel---just aint there long enough.

If you had to clean the lead splatter out of my muzzle brake with an ice pick and a chore boy you'd have no doubt the flame and pressure blows molten lead all over the place...even the top strap.

[Lloyd Smale]

Nothing will prevent leading if you have a missmatched bullet. If your bullets are sized properly for your gun gaschecks will allow you to shoot at higher velocitys without leading and will usually give you better acuracy. Probably due to the fact that you have a more consistant base for the gases to push on.

[Bret4207]

If you had to clean the lead splatter out of my muzzle brake with an ice pick and a chore boy you'd have no doubt the flame and pressure blows molten lead all over the place...even the top strap.

It's not melting, it's eroding it and the alloy pushed off adheres the the metal. It's seems like "melting" is the term many use to describe this, but it isn't accurate. If you go back through the older posts here you'll find dozens discussing this at length in depth. There just isn't time for the metal to melt.

[44man]

Thats correct, the lead does not melt but is stripped from gas jets working on it. After all, they can cut metal with water jets!
Another thought about gas checks is how they work when fired. If you take a good look at the base of a PB, fired boolit you will see lead has been extruded to the rear to form fins around the edges. Not a problem with a good fitting boolit or one that is started straight but if a boolit starts a little off, the extrusion will be greater on one side then the other. When it leaves the muzzle it will be blown sideways by escaping gas.
The gas check helps hold down the extrusion to some extent.
I shoot all heavy loads in my revolvers with both PB and GC boolits and I can't detect whether one is better then the other. Leading, what tiny amount there is, never changes. A few tiny strands on the first patch no matter how many months between cleanings. Accuracy is the same with either boolit.
It makes me wonder if paying for the checks is worth it. Maybe in the real high pressure stuff like the .460 or .357 max.

[Papa smurf]

bhp9 ---- Very good read. Your right on the money!

[pps]

It's not melting, it's eroding it and the alloy pushed off adheres the the metal. It's seems like "melting" is the term many use to describe this, but it isn't accurate. If you go back through the older posts here you'll find dozens discussing this at length in depth. There just isn't time for the metal to melt.

That's fine, I'll concede to calling it eroding. The end result is the same in the sense that a bullet to small for the bore will allow more of the gas to rip lead off the bullet and deposit it all over the barrel.

[Dale53]

44man;
I NEVER use gas checks on .44 magnum or .357 magnum full loads and I have NEVER had a leading problem. I DO use properly fitting bullets. Well, I lied just a bit - I have on occasion used the Lee .430-310-RF and it is a gas check bullet (wonderful accuracy with that bullet, by the way) and it is the heaviest hitter that I have used in the .44 magnum.

However, my biggest game with handguns has been large whitetail deer. The .44 Keith does a fine job on these. Dead is dead. If I hunted bigger game with a handgun I definitely would use the Lee. Frank Siefer and I designed this bullet and it turned out to be a wonderful performer.

My "go to" bullets are plain base for ALL of my revolvers. I recently acquired a .454 Casull Taurus Raging Bull (what a name:groner:) and WILL be using Lee's gas check 300 gr RF bullet in this as the velocities will exceed 1600 fps. Up to 1400-1500 fps, there is really no need for gas checks, in my experience, and with the recent cost increases, that only makes me HAPPY!:p Even with the .454, no doubt, my practice bullets will be plain base bullets driven no faster than 1400 fps.

Dale53

[Ricochet]

Lead that's eroded off the sides most certainly IS melted. Or can be. I still have a few drops of it soldered onto the bayonet of a Mosin M91/30, after spending a lot of time and vigorous effort chipping and scraping the bulk of it away. Water dropped wheelweight .315" plain base Fat 30 TL plinkers lubed with LLA, run at ~2000 FPS over IMR 7383 is what did it. Funny thing is, it didn't lead the bore, but it COVERED the proximal bayonet with splattered lead!

[jonk]

I would dispute that a bullet cannot melt. I agree generally it doesn't but allow me to relate...

A few years ago I was shooting a 6.5 Carcano with surplus ammo. A lot of hangfires. One round apparently wasn't charged with powder at all (sabotage? Or just crappy Italian quality control?) The primer alone had enough oomph to drive the cupro-nickel clad lead base bullet into the rifling and lodge it there. Fortunately I noticed this.

I was about 20 rounds into things when this happened, fired over perhaps 5 minutes. The gun was pretty hot but not smoking or anything.

So I go and get a rod out of the trunk and a small hammer and tapped the bullet out. I'd guess it was lodged in the rifling for 2, maybe 3 minutes.

Upon driving it out I found that a bead of lead had melted out the bottom of the bullet and re-hardened when it reached the chamber. So the temperature in that barrel had to be 500 degrees or so. After just 20 rounds of high power rifle ammo. Over 5 minutes. Through a fairly thick cupro nickel jacket.

This suggests to me that if you fire off a string rapidly and chamber a round it most definately COULD get hot enough to melt, perhaps in the chamber, certainly if engraving the rifling. Not that that happens to most folks, I'm just saying it can.

[docone31]

Here is where I wonder. I have noticed, when soldering steel, or iron, I have difficulty unless the proper flux is used. I wonder if the leading is more planishing. That would explain why with a tight fitting bullet, there is little as compared to one that is more loose in the bore.
I see it in the jewelery I make. With polishing I planish rather than grind away. Gold, and silver, shows the same drag marks as in the photo when it is first started.
There is tremendous pressure behind the bullet, as well as the extrusion on the bullet traveling the bore. Even on my high polished tools, I see the same traces although more microscopic. This could be that lead is softer than the materials I work in.
No matter what, it is certainly an issue. I have just loaded 20 test bullets for my .303 British. I am hoping it will not be time for major elbow grease! I only did 20, and I plan on firing a few commercial loads to scrape away anything really major.

[Ricochet]

I have noticed, when soldering steel, or iron, I have difficulty unless the proper flux is used.
I've noticed that, too. Apparently a mixture of gun oil, burned LLA and IMR 7383 residue makes a pretty good flux on blued steel.

[leftiye]

Plus one as to boolits can and do melt in the barrel. Both from heat of friction, and flame temp, also due to flame temp while blowby is occuring. There was a post recently where the info was about someone actually using some apparatus to read the temp of a bullet just leaving the bore. It tested out at 500F plus FWIW. Bullet temp. I think it was JoeB on his thread "Do cast boolits blow up? who posted it. Flame temp of 50,000 psi loads has been known for over 40 years to be 4000F.

[454PB]

Dale 53, you're gonna establish a new relationship with gas checks if you push that RB to it's full potential!

I've had one since they first came out. Yes, you can certainly use your light loads without GC, but the ones pushing 60K really like them.

[Bret4207]

IMO you are confusing melting with eroded lead particles adhering to the metal. Yes, it looks like drops of solder, but it isn't. I think the lead is eroded off and the atomized particles are forced against the metal under great pressure. The soft alloy will adhere to the imperfections in the barrel. In truth it may as well actually melt, there's no practical difference from what I can see. There's also the issue of the lead alloy galling into the barrel. Anyone who's ever slid a file across anything sees what is happening. The imperfections in the relatively hard barrel allow the lead alloy to gall and remain in the barrel. Again, it may as well be melted. Same with Ricochets lead spray on the bayonet- atomized lead eroded off the boolit at great pressure adheres to the steel like a soft snowball thrown against a barn wall.

As for the temps and pressure involved, there's no doubt it's as hot as posted. The problem becomes one of time. The time it takes for heat to transfer to the alloy and heat it to the melting point is considerably longer than the time the boolit remains within the confines of the barrel, or so it is reported. I don't know what the actual time is and I imagine it varies with load, bore size, boolit alloy, etc. We're talking micro seconds and any thing between the boolit and flame like lube, COW, dacron, etc. will add to the needed time. It's pressure and poor fit that causes leading boys.

All this means nothing in the real world. Leading is leading and we know how to prevent it, what causes it and how to remove it. All we're doing here is defining a point.

[MT Gianni]

For those in the "it melts Camp", try putting some grease on the bottom of a gas check, loading and firing it where the check can be recovered and then please explain to me why it doesn't melt grease. Gianni

[runfiverun]

i think swaged under pressure is a more apt description.

[NSP64]

Barrel smoothness, fouling, and forcing cone all play a part in whether a barrel will lead.

[NSP64]

After all, they can cut metal with water jets!

Seen some Navy boys try to cut a mountain with a jet.[smilie=1:

[carpetman]

You have friction,you have primer blast,you have burning powder,you have pressure and I heard somewhere you have rpm. But you only have .00001 or some such seconds to do it in and you are going to melt lead? If you can you need to be designing cutting and welding equipment because you are much more efficient than anything that currently exists. You can train a ******* all you want but you aint going to win the Kentucky Derby with one. Take a lubed bullet and hold a torch to it long enough to get some melt? What happens to the lube. It becomes liquid,burns smokes and chars. Recover a bullet that has been shot. Lube is still there in the groove and it aint ashes---it's still lubey. Some may say lubey is not a word,but it is now,I just invented it and I must say it's a good word as you all know what I meant by it. Invent your own words and nobody can say you misspelled it. Back to the lubey lube---had it been subjected to enough heat to melt lead there would be no lube. It would spin off from the rpm's like a dog shaking water off. BTW--that was not the first word I ever invented---I have as much right to invent words as anybody else---doesn't require a license. Here's one of my all time favorites. Boobacious. She is a very boobacious lady. Everybody gets the meaning---a good word.

[Bret4207]

I invented "snogwoggin". I was drunk at the time and don't have any idea what it means and neither did the guys with but one of their wives was really, really mad at me for a long time.

[Ricochet]

Gianni, the grease on the base is protected by a thin stagnant boundary layer of gas that insulates it from the greatest heat. When gas is forced through a narrow channel at high velocity, that boundary layer is blown away.

[Red River Rick]

When gas is forced through a narrow channel at high velocity, that boundary layer is blown away.

Ricochet:

We are talking about bullets hear, aren't we?

RRR

[quasi]

Rotflmao!

[unclebill]

snogwoggin eh?
sounds risky with another mans wife!;)

[44man]

I pick up unburned tufts of dacron in front of the bench. With black powder I pick up handfuls of thin plastic wads that are just dirty, also thin ,.005", paper wads that are not burned after being on top of 74 gr's of compressed powder.
I suppose if you shot full auto and got the barrel glowing, you might start to melt lead but it will be from retained heat, not from the actual firing process.
There is just not enough time to melt or burn anything
Then some of you might use a SLOOOOOOOOOOOW powder! :kidding:

[Ricochet]

Y'all are theorizing. I'm telling you what I've seen. Come down here and I'll show you, I can reproduce it in that Mosin with no problem. I'd appreciate it if you cleaned up the bayo, though, I've worked on it a lot from last time I did it and still don't have it all off. (I don't want to melt it off and risk ruining the temper of the bayo or its catch spring.)

I believe those of you without fixed bayonets can set up a similar situation firing beside a parallel rod with plain based boolits and a large charge of slow burning rifle powder. Just might see the same thing. Or fire through a hole in a barrier that would catch the slung droplets.

[pps]

Y'all are theorizing. I'm telling you what I've seen. Come down here and I'll show you, I can reproduce it in that Mosin with no problem. I'd appreciate it if you cleaned up the bayo, though, I've worked on it a lot from last time I did it and still don't have it all off. (I don't want to melt it off and risk ruining the temper of the bayo or its catch spring.)

I believe those of you without fixed bayonets can set up a similar situation firing beside a parallel rod with plain based boolits and a large charge of slow burning rifle powder. Just might see the same thing. Or fire through a hole in a barrier that would catch the slung droplets.

I don't care how it gets there (melting vs eroding the lead) I just know that I had some THICK deposits in my compensated tip...that I don't need for 38's anyway. The worst of it, after 100 rounds was just shy of 1/8" thick and needed an icepick and choreboy to remove.

Now that I bell the cases more, and no longer shave the boolits, no more leading, even with the Hornady swagged. With any new lead boolit I will make sure is sized right.

[Larry Gibson]

Carpetman

Very well put. The problem is many of the "experts" here don't want to here about actual tests or actual facts. They prefer abstract notions, opinions, cantations and quoting or rehashing some other "experts" same. No sense trying to talk sense to them, ask them to look at facts, tests or to even conduct their own tests; they prefer to huddle around their cauldron (keyboard) make another brew.

You, I and many, many here don't claim to be such "experts". We prefer to look at what really happens and conduct analytical tests to determine what happens. We do not set ourselves up with “a few of us can” attitude. We genuinely try to understand the loading and shooting of cast bullets. We do not set ourselves up as “all knowing’ guru’s.

Loading and shooting cast bullets is not difficult. Getting good accuracy with them is not difficult. One merely must understand there are some rules and or principles that apply. Violate those rules or principles and something can happen like leading. Some would have us believe good cast loads only happen when the stars are in proper alignment with Jupiter or some such nonsense. Some designs of cast bullets shoot better at low velocity, some shoot better at high velocity, some will lead at low velocity, some at high velocity. There are some lubes that work at low velocity and some at high velocity and some work in both. One simply must match the correct components to the rifle/handgun, there is no magic about it.

My point here is; you are right.

Larry Gibson

P.S. I really like your word!

[leftiye]

One of the rules is that a question deserves an answer. Called straight talking, and common decency.

[BAGTIC]

(1) It is not the water that allows water jets to cut metal, etc. It is the abrasives carried by the water jet. The jet is just a carriersthe way the belt carries the abrasive on a belt sander.

(2) Leading does occur. It is not caused by the lead melting. There simply is not time. Fasten a lead bullet is a vise and very quickly, as quick as possible, direct an open flame such as a propane torch across the base. Mop up the drops and send them to us.


(3) If the lead were melting it would be distributed rather evenly inside the barrel. Most all leading begins in the bottom of the grooves where it collects after being stripped off. When we use our metal files in the shop are we be believe that all the crud that collects in the grooves is there because it melted off?

(3) One of the common solutions to leading is to use a harder alloy. Why? The harder alloys often melt at lower temperatures than pure lead. If melting was the cause they should melt faster not slower and cause more not less leading.

(4) Using a slower powder is not going to 'bump up the bullet' better. It is not muzzle velocity that expands the bullet it is peak acceleration. It is necessary to have maximum initial acceleration because that produces the most G's and we want the maximum speed at the time the bullet enters the barrel. That is where the expansion takes place, not halfway down the barrel.

(5) Undersized bullets are not leading because a gas jet is cutting the sides. Gas escaping from an orifice (windage) is cooled and actually lower that its original temperature.

(6) Lead collects in the grooves because that is where the empty space is. It is not going to collect somewhere that is already filled.

(7) Undersized bullets provide such a space and because they are not an interference fit the permit more canting of the bullet so that the corners of base has more chance of being scraped off.

(8) The bullet will be heated more by the deformation of being swaged (bumped) up than by the powder gases themself. When a metal is reformed (forged) internal heat is generated throughout the object, not just at the surface, by hysteresis. That is why impact extrusion manufacturing works.

That is why if you shoot a metal plate and immediately stick you finger in the cavity it is hot. The heat was not caused by heat from powder gases yards away. It was caused by the physical reforming of the metal.

(9) A grain of sand is a particle. If the sand is melted it is a droplet. Particles of soft material, such as lead, will splatter and adhere when impacting at high velocity. Throw a mud ball against a house, did any of it stick. Was it melted?

If the lead was melted how did it stay melted during its entire passage through the bore? Chamber pressures and chamber temperatures peak after just a few inches of bullet travel. During the rest of the trip both pressures and temperatures drop very rapidly.

Good thing that expanding gas cools, otherwise our car engines might melt.

Many of us have had leaded bores. Usually we discover it when the accuraccy goes sour and we look down the bore. I have had a 6" .357 revolver barrel leaded so badly that the riflings were totally invisible the last 2.5-3 inches of the barrel.

Seldom do we check the bore after each and every shot to see which round did the dastardly deed. If we did we would probably learn that no single bullet did it. Instead it was an accretion of fouling from several shots. Now what would happen if we cleaned our barrels after every shot. One thing is that the lead would not have a chance to accumulate and each round would start with a relatively clean bore.

I believe that is the primary function of gas checks. They act like the oil scraper ring on a diesel engine piston. It scrapes off the leading deposited by the fore part of the bullet and prepares a clear bore for the next shot.

Can I prove it. NO! But at least it doesn't contradict the laws of physics.

[Larry Gibson]

pps

If you were shaving the bullets with the case mouth when seating the bullets and got leading (severe BTW) then it is obvious you were scraping (shaving) the lube off. This is evident by the fact that with a proper bell of the case mouth th bullets no longer scrape and you no longer get leading in the barrel. That is in effect a "test", i.e. effects of leading with and without a good case mouth bell. you narrowed the parameters down, located the problem and eliminated the problem. I know you did not intend on conducting a test but merely wanted to end the leading. The result was the same. Your results are "facts". As Ricochet points out "to many are theoirizing" instead of looking at simple facts.

Good job getting the problem solved.

Larry Gibson

[Larry Gibson]

One of the rules is that a question deserves an answer. Called straight talking, and common decency.

Ask a straight question then. I'll give you a straight answer. Don't bellyache and whine if you just don't like the answer as you most often do. You ask the question, I'll answer. That simple enough for you?

Kindly; If it applies on this thread then do so here. If it applies on one of the others please post there. If you want a new thread, start one.

Larry Gibson

[sundog]

Seventh Grade National Championship Spelling Bee ---

Little Johnny approaches the microphone.

Little Johnny, your word is 'boobacious'.

Little Johnny's face get seriously screwed up!

Boobacious. What part of speech is it please?

It is an adjective.

Boobacious. Can you use it in a sentence please?

Boobacious. Carpetman has a boobacious avatar.

What is the origin please?

Carpetmanian.

Suddenly, Little Johnny's face has a sly smirk...

Thank you. Boobacious. B-O-O-B-A-C-I-O-U-S. Boobacious!

[Bob Krack]

1) It is not the water that allows water jets to cut metal, etc. It is the abrasives carried by the water jet. The jet is just a carriersthe way the belt carries the abrasive on a belt sander.

(5) Undersized bullets are not leading because a gas jet is cutting the sides. Gas escaping from an orifice (windage) is cooled and actually lower that its original temperature.

Ever see a "Plasma Torch"?

(6) Lead collects in the grooves because that is where the empty space is. It is not going to collect somewhere that is already filled.

(7) Undersized bullets provide such a space and because they are not an interference fit the permit more canting of the bullet so that the corners of base has more chance of being scraped off.

The leading edges of the engravings are scraped and the trailing edge is 'thrown" off - and the softer the projectile (and/or the less capable lube), the more is scraped off..


I believe that is the primary function of gas checks. They act like the oil scraper ring on a diesel engine piston. It scrapes off the leading deposited by the fore part of the bullet and prepares a clear bore for the next shot.

You are probably 99.9% correct there!

A gas check also supplies a uniform shaped base - that is - no sprue cut, no tall side because of the sprue cut, no deformation from a slightly molten base at the sprue.


Can I prove it. NO! But at least it doesn't contradict the laws of physics.

Me Too!
Vic

[Lloyd Smale]

Im far from a scientist and wont do much therorizing here but my thought goes to the non melting side. Smokeless powder burns it doesnt explode so a good part of the bullets path down the barrel is cushiioned by unburned powder. Now this may not be the case with bullseye or other fast burning powders but when were talking leading its usually high performance ammo with cast bullets shot fast and in those cases your usually using a relitively slow burning powder. Personaly i think its more the friction tearing off lead and ill fit bulets cause it and the faster you shoot them the more it shows up. I can take one shot out of an ill fit gun every day for a month and see leading and the barrel isnt even showing signs of being warm after one shot. Once you get a trace of lead in your barrrel its just going to keep attracting more lead as the next bullet passes over it. Im even having second thoughts as to how much lube plays a part in actually lubricating a barrel to prevent this friction after recovering about a 100 bullets out of the snow this year lubed with a lube at least as soft as javalina and seeing how little lube is actually used. I was allways followed the group of people who believed the bullet being shot was lubed by the lube left in the barrel by the previous bullet. But seeing how little lube is used and the ammount of smoke you get with a aloxed based lube id about bet a dime to a dollar that any lube put down by a bullet going down a barrel is burned away while that bullet is being shot. Maybe enough lube and burned residue of lube is left behind to create a barrier that helps prevent the lead from sticking somewhat to a barrel but what makes me doubt even that is what flux does in soldering is block oxegen from metal to allow two metals to stick and bullet lube and soldering flux are very simular as some fluxes are wax based so why wouldnt it actually allow for the lead and steal to stick together even more especially if you were in the camp that believes that lead melts in a barrrel. then theres this thought. If your soldering metal the lead wont stick until the metal your soldering it to is about red hot. So how does it stick to barrel metal when shot in a cold barrel. i surely dont know the answer to this leading thing and what lube really does in a barrel. I dont think anyone really does and mostly all of this is just a matter of opionion mostly gotten from other people back when there was no real way of testing to prove any of it. All i know is lube is a neccisary evil in shooting cast bullets. Whatever its doing in my barrels is needed and i guess it really doesnt matter to me and its not worth lossing sleap over or getting wound up trying to argue my point. it is because it does and does because it is and thats good enough for me.

[rhead]

When a small piece of led is removed from the bullet by gas cutting it will be surrounded by the hot gasses and no longer protected by the realitively massive heat sink of the bullet. In this enviroment it may have time to melt into a microscopic droplelt or maybe a nearly melted particle. If this particle inpacts something and stops (the inside of th barrel or a fixed bayonet) its kinetic energy will be released as heat and leave a small droplet waiting to get ironed onto the barrel by the passing bullet. The melmay be occuring after the leat is removed from the bullet.

[Bass Ackward]

ROTFLMAO

Two shooters standing on a street corner theorizing.

First one is discussing an issue and is therefore theorizing. The second guy is theorizing if he is wright or wrong. :grin:

Makes shooting sort of like politics if you think about it. :grin:

[Newtire]

Boobacious. She is a very boobacious lady. Everybody gets the meaning---a good word.

Carpetman, it is "Boobalacious" to be correct. "He admired the boobalaciosity of the lady." (or here in California-could be a guy also)

[44man]

When a small piece of led is removed from the bullet by gas cutting it will be surrounded by the hot gasses and no longer protected by the realitively massive heat sink of the bullet. In this enviroment it may have time to melt into a microscopic droplelt or maybe a nearly melted particle. If this particle inpacts something and stops (the inside of th barrel or a fixed bayonet) its kinetic energy will be released as heat and leave a small droplet waiting to get ironed onto the barrel by the passing bullet. The melmay be occuring after the leat is removed from the bullet.

Now this is something I never thought about. Tiny droplets could very well be melted. But how would it stick is the question? If a fouled barrel was sectioned and you used a soldering iron, I don't see any way you would get solder to stick without going to bare, clean steel first and using a good flux. Even the wrong flux or using a flame on the wrong flux thats burns will prevent soldering.
I have been soldering for 60 years, started as a kid making toys and yes, the metal must be super clean and HOT before anything sticks. Metal must be at least to the melting temperature of the solder. If cold, a piece of lead might stick but you can pop it loose and any part that is soldered onto cold metal will fall apart.
Leading a barrel by soldering melted lead into it would be like soldering copper pipe together using a light bulb for heat.
I know a lot of you have tried to do plumbing when there was some water in the system! :groner: Even one drop turning to steam will stop you short.
I have soldered sights on and removed soldered parts from military rifles and I can tell you that you will not touch the metal.

Now there is something else going on and you can see it with a boolit mold if you cut a soft sprue. Lead will stick to the plate and top of the mold even though neither is hot enough to solder nor is the lead molten. In fact if you really wanted to solder on a mold block it needs to be much hotter and clean with a good flux used.
So maybe we should look at barrel leading the same way we look at the top of our molds.
Could it be called "mechanical" soldering? Do the droplets forced from the sides of an undersize boolit just get mechanically force soldered to the steel?
OK, we use Bullplate to prevent the problem with a mold. Seems to me the boolit lube is doing the same thing in the bore and is why a wax coating alone on a boolit will work, providing a barrier against "force" soldering.
How about the lead on the bayonet! I picture the end of the muzzle acting just like a cylinder gap at the instant the boolit exits, blowing gas pressure and any lead droplets/pieces sideways to impact the steel bayonet.
Does this lead really have to be melted to stick to the steel????
Anyway, I think everyone is looking at it all wrong, thinking it is HEAT soldering and the lead is molten and the steel hot enough to solder.
Have I got you thinking yet? [smilie=f:
I think Rhead is correct in describing what happens but I have my doubts that the lead is molten, but who knows?

[looseprojectile]

I have read all the posts in this thread a couple of times and I think I have learned something. Very entertaining.
Most of the posters have some good points and should be given some consideration.
I conclude that the simple presence of "FRICTION" causes leading. Reduce friction with lube or alloy and no, or reduced friction and leading occurs.
Now someone splain how making the boolit fit tighter in the grooves results in less leading, or friction. Maybe a combination of lube, less gas cutting and such?
Many of you arent old enough to remember when the gummint would allow we the people to keep and bear, "strike anywhere" matches. These matches could be struck [using their term],on the seat of your Levi's. By rubbing these matches briskly on just about any surface they would get hot and ignite from the FRICTION.
Shucks, just rub a knuckle on your pants really fast and you will get the picture.
Friction causes heat. The more pressure and speed that is applied the more HEAT.
Absoutely "INSTANT" heat.
Gots my asbestos suit on.
Life is good

[44man]

Yes, but would your hot knuckles melt a boolit? I have picked up thousands of boolits and I can't find any sign of melting. I HAVE seen too small of a boolit etched by gas.
If the surface was turning molten the boolit would never take the rifling. Remember the barrel friction is so short in time that nothing really happens. The mass of the barrel sucks up the heat. Shoot a high power rifle fast and pick up a case, it is hot but but it won't burn your hand or melt lead.
I don't know if any of you have shot dead soft .38 wadcutters much. But they would pack a bore full of lead and the rifling would not be seen anymore. The outside of the cylinder would also be packed with lead. And yet guys here shoot lead to over 2000 fps in rifles with no problems.
You have to admit something else is going on other then melting and I still say it is impact and roll over soldering.
Then there is the really funny thing. Shoot a steel plate with a high velocity cast boolit and the boolit explodes but there is no soldered lead on the plate???? Just a splash. In a few days the crater will be all rusty. Why didn't lead solder the surface and protect it from rust? Why didn't the extreme heat transfer solder the steel?
Hey, I am getting a headache! [smilie=b:
I forgot to add that the compound in the matches was very sensitive and also had an abrasive cast into it. If you remember, just a slow rub on a rough surface would light them. Very little friction heat needed.

[leftiye]

Lloyd - Gawd! And I'm a past master of the run on sentence. Kudos, man!

[looseprojectile]

a lot like skiis allow one to slide on snow, in addition to making the boolit fit better.
Gilding metal is more slick than lead alloy? More slick with a grease interface?
For those of you in more southern States, how about this. You are on pavement in your car, going 60, jump on the brake pedal, you leave rubber on the road, the tires are heated, the road will be heated also. Equate road with barrel and tires with boolit. Is this a different concept? We would probably experience some of the same effect if the tires were lead and the road was smooth steel. Now, how about greasing the whole mess. Less friction, less heat and we have not burned up a significant amount of grease. 44 Man. have you recovered any boolits shot in a badly leaded bore? I think I am through with the analogies now. Can I go out and play?
The more I think about this the more thoughts I have about the projects that I have to do in the shop, such as loading some 45 70 and 40 65 ammo.

:castmine:
Life is good

[scrapcan]

I have say the water can be used alone to cut in a water jet. you may not cut really hard material, but look at your next single slice cheese or pre- cut lettuce, more than likely it was cut with a water jet cutting machine.

I have other examples also but that should suffice to explain that water is very abrasive in and of itself and it is way off topic of theis thread.

[leftiye]

One thing not said here yet is that the heat, however much there may be is CONCENTRATED on the surfaces of the metals due to the short time of passage (that everyone is saying prevents enough heat transfer to happen to do anything). Lead tranfers (carrys heat to cooler parts) slowly, but even steel cannot transfer heat fast enough to overcome the heat buildup in these circumstances. Witness the "Nitriding" that is the main issue in flame erosion in rifle throats. The 4000F degree flame melts the first thou or so of the metal, introducing nitrates into it. The metal becomes more brittle due to this, and flexing of the barrel under pressure causes microscopic pieces to break off. And that's not lead, it's steel.

I also think that 44 man's illustration of lead "smearing" on a sprue plate is a pivotal concept here. Not exactly soldering, but almost identical. No doubt if there was a microscopic layer of hot lead on the outside of a boolit it would do the same thing IMHO.

And last but not least - Galling. Rub two pieces of metal together SLOWLY (or not so slowly, whatever, it's not about speed like it usually is with friction.) with great pressure, and the softer metal will melt and weld to the harder metal. Not smear on, weld (or in the case of lead/steel "solder"), You'll have to treat steel that has galled like one piece and machine or file it off, (no parting line between the different pieces). And, yes, that is heat too.

I suggest we consider all of these in concert as well as other factors in this search foe the cause of leading. Super thread, very enjoyable.

[looseprojectile]

Leftiye
Now we are getting somewhere. I can imagine the interface tween the boolit and barrel needing something to reduce friction. What would be best for doing that?
Light oil? Heavy grease? Wax? Molybdenum disulfide? A combination of these?
I think that the heat from friction, not transferred to the body of the boolit, is the problem in cast boolits that lead the bore. Maybe confine the heat to the boolit?
The boolit fit and lessening the friction is the goal.
That infinitesimal surface is where it all happens.
Some would say my mind is small enough to get it in there.
Life is good

[44man]

This has been a great subject with a lot of interesting theory's. I can't say anyone is wrong or right because we just don't know what really happens. I feel this post can go on forever and we will still never know.
But I am glad to see how everyone puts in their two cents without any friction between each other.
You are all gentlemen! :mrgreen:
Keep trying to figure this out because it is the most important part of our sport.
Looseprojectile, no, I never recovered any like that because those boolits were shot indoors at a police range and I would clean some of the guns for them. Holy smokes, talk about leading! I have never had a gun in my life get so bad. Those were all factory loads too. Just goes to show that even light, low pressure loads can be worse then 60,000# loads.
All agree that the boolit must fit the throats and be larger then the bore. However I shoot .430 boolits, medium hard cast, from my .44 with hot loads and they do not lead my bore. My throats are .4324".
What we have is called a mystery---I can't spell voodoo! [smilie=1:

[Bret4207]

Leftiye
Now we are getting somewhere. I can imagine the interface tween the boolit and barrel needing something to reduce friction. What would be best for doing that?
Light oil? Heavy grease? Wax? Molybdenum disulfide? A combination of these?
I think that the heat from friction, not transferred to the body of the boolit, is the problem in cast boolits that lead the bore. Maybe confine the heat to the boolit?
The boolit fit and lessening the friction is the goal.
That infinitesimal surface is where it all happens.
Some would say my mind is small enough to get it in there.
Life is good

If I follow you correctly then I have to disagree. I regularly shoot as cast "oversize" boolits, as much as .005 is one particular rifle. The grooves are filled before the lands even distort the metal into them. If there was going to be "friction" it would come into play and I'd get leading like crazy. No such problem exists at the speed I'm shooting and with the loads I'm using. These PB boolits pop out the muzzle well over 1200fps with zero leading. Gotta be lube helps a bit I'd think and I still use plain jane 50/50 NRA formula.

If I misinterpreted what you said then please straighten me out.

[leftiye]

Bret, not to have my nose where it doesn't belong... I read Loose projectile as saying that lube WAS needed and beneficial. You two may in reality not disagree.

[Boomer Mikey]

The following is paraphrased from an article by Dave Scoville in the 1991 Bullet Making Annual in Wolfe Publishing’s “The Art of Bullet Casting DVD”. Available at their website and MidwayUSA.

Leading: “It may be the result of a number of factors, such as fusion, gas -cutting, friction, inadequate lubrication or skidding."

"The gas-cutting/skidding problem crops up when the bullet can’t maintain a solid purchase on the lands as it begins to accelerate through the bore. As the first driving band contacts the rifling, it tends to slide across the lands as momentum carries the bullet straight ahead. As successive driving bands take on the lands, the bullet begins to respond to the rate of twist but is still skidding. By the time the base band enters the barrel, even the slightest amount of skidding opens a gap between the lands and respective engraving on the driving bands. Hot, expanding gasses now have an opportunity to escape and burn through the gap and across the base band. In the process, alloy is deposited along the edges of the lands. As more rounds are fired, the leading is moved progressively toward the muzzle until the bore is literally lead-plated from one end to the other.”

The four most common approaches to eliminate gas-cutting:
1. Use a harder bullet
2. Cut back on the powder charge
3. Use a slower powder to reduce the rate of acceleration
4. Use a gas check – but if the bullet is skidding badly the gas check can’t control the volume of lead

“The challenge to cast bullet shooters is to hit that happy medium between too much pressure and not enough.”

Paraphrased: Too much pressure/lack of lubrication will result in leading at the muzzle and too little pressure will result in leading at the chamber/throat due to lack of obturation.

Fusion:
“Fusion is usually associated with plain-based handgun bullets and is the result of using too much fast-burning powder which generates heat and pressure very rapidly… It crops up in various degrees, from bad to worse and causes leading when the molten lead is blown down the barrel behind the bullet, literally plating the bore.”

“To eliminate fusion, there are three basic choices: Back off the powder charge, use a slower-burning propellant, or switch to a gas-checked bullet… Fusion also seems to be most apt to crop up on bullets cast from Linotype, which is not only harder than most alloys, but usually carries six or seven percent tin as well. From available evidence, the relatively low melting point (463 degrees for Linotype) and high tin content seem to be the common denominators when heavy doses of fast burning pistol powders result in fusion.”

Lubrication:
“Be careful when tempted to blame inadequate lubrication for barrel leading. Most cast bullet designs carry sufficient lubrication if the bullet is hard enough to withstand the pressures and velocity involved. The trick is to make available lubrication last until the bullet reaches the end of the barrel. In most cases, as velocities increase, that requires increasingly harder bullets – not more lubrication grooves at the expense of bearing surface… Use Alox blend as a standard and increase the load’s velocity to a point where some evidence of leading is visible, then repeat the same loads with other lubes. Assuming the bore is smooth and free of fouling from jacketed bullets, it is not unusual to find one lube provides lead-free performance and fine accuracy while others don’t. Keep in mind that other variables, such as bullet sizing, may be influencing the results” (larger diameter bullet size may improve lube retention [bm])

Gas-Checks:
“Gas checks serve as scrapers and insulators. They help reduce or eliminate leading to a considerable degree with appropriate loads in both rifles and handguns. On occasion, they may create problems where none existed before… Gas checks, being somewhat harder than lead alloys, tend to restrict base expansion and may allow combustion gasses to sneak by them and attack the surface of the base band.” (sized too small for the groove diameter [bm]) “If leading gets out of hand gas checks simply won’t be able to control the alloy build-up”

“For big bore rifle shooters who prefer cast bullets in cartridges like .375 Winchester, .38-55, 45-70 and others, wax gas checks appear to be equally effective… More importantly, whenever wax gas checks are employed, groups are remarkably consistent.”

This article; for me, was well worth the cost of the DVD set…$25.00.

I thought this might add some material to think about for the discussions in this thread. Not to be construed as the definitive answer but to add the point that there is no single cause of leading and that gas checks and larger/harder boolits aren’t always the cure. The article is too extensive to post, these are merely some highlights.

Boomer :Fire:

[pjh421]

I wish I would have had the benefit of threads like this back in '94 & '95 when I was a new caster and was shooting every day.

Paul

[looseprojectile]

Bret;
This thread started with the gas check theme and I tried to wrap my thinker around that.
I have been trying to escape the use of checks as I am income challenged.
Lately I have discovered LLA and use it in wheel guns and rifles above 40 caliber with good results. No more than 1300 - 1400 fps. This is with pb boolits. I may alter the lube also.
I believe I have a reasonable understanding of what it takes to get accuracy and a clean bore at this juncture. Previously I had been expecting more power/velocity from rifles,with boolits and it don't work that way. I have realized that , if you need more power you may need to go to a high intensity cartridge with a full length gas check. Gots those also.
Life is good

[docone31]

I agree, this has been a great thread. A lot of information here.
Steel, and stainless steel barrels are actually porous. Although microscopic, there are a lot of holes on the surface layer of steel.
I am inclined to lean towards planishing.
As the bullet travels down the barrel, microscopic imperfections get a deposit. The lead is under tremendous pressure, and friction.
I have soldered ribs on barrels. It does take work, and just the right amount of heat, and flux. I am not sure, the interior of the barrels get hot enough to solder. There is heat, caused both by powder burning, and friction, however, only the bullet is under constant friction.
Nuff said by me. I have no imperical evidence to either disprove, or prove anything here. I do know, I have the privilege of reading the writings of people, who have both the experience and the desire to pass it on. Both pro and con. There is a lot of experience here, and a lot of fun just reading.
I have learned enough, from reading from this forum, that maybe this time.... I just might be able to diagnose whats up when I cast, reload, and just make a mess. I got discouraged years ago and went to jacketed only. Economic times almost make it a certainty that I will have to cast. I just got my new 185gn .312 mold from Lee. I look forward to giving this a try. I was only groping in the dark before.
I have probably picked up more information on this thread than I had learned all those years ago.

[WineMan]

Just an observation but I used a lead (WW) ingot to cushion the rifle barrel on a Russian M-38 to drift the front sight. After moving the barrel around to get it in the right spot I had numerous streaks of lead that I was unable to remove with a cloth. I had to use a brass brush to get them off. Amazing that it was so tenacious. It surprises me that barrels are not chock full of lead after a few shots.

Wineman

[MT Gianni]

Tight fit vs Loose fit: When a knife is sharp it cuts smoothly, ie with no or little friction. When a knife is dull, or has an edge with gaps and uneven wear it cut a jagged, tearing cut. Could it be that a loose [undersized] bullet is actually seeing a tearing action off of sharp edge rifling, uneven bore sizes and friction ensuing there? A tight fit would eliminate the movement of 0.0001 and the resulting expansion and wiping/tearing that results in more frictiom. Gianni

[Bret4207]

Bret, not to have my nose where it doesn't belong... I read Loose projectile as saying that lube WAS needed and beneficial. You two may in reality not disagree.

Okay, now I see (said the blind man!)

I think we're all mostly on the same page here. People tend to hear "melting" and think of wax like melting. Just ain't so. Call it planishing, galling, impact sticking- it's all the same.

As to the GC itself- I think it does work as a scraper in tight enough bores. But I also shoot an 8mm GC in a .333+ bore with zero leading. So I also think at times it functions differently.

[Bob Krack]

Okay, now I see (said the blind man!)

GranPappy always said -
Okay, now I see - said the blind carpenter as he picked his hammer and SAW!

Vic