Gas checks

[plaz]

I am new at this. I would like to know something about gas checks. When should I select bullets that use gas checks? When is the use of gas checks recommended?

[Crusty Deary Ol'Coot]

Wide open question, plaz, and you will get a bunch of answers.

Normally the long excepted answer would be that plain base is for low velocity loads and Gas checked for high, but that is not always true.

It is said by some that boolits with GC are easier to make shoot well, but this is again not always true.

Personally, I shoot a GC boolit for such things as my RUGER #1 - 45/70, and the 310gr LBT boolit I shoot in the .44 Redhawk.

I have a new LBT mold on order for the 45/70 and this will be for Gas Checked boolits.:lovebooli

I also have one GC mold in .44 at about 250gr, but also have a plain base mold in about the same weight.

I Shoot a plain base boolit in my 38/357, the same boolit for both 38 and 357 loads.

And of course the 45acp gets a plain base.:cbpour:

As you get into specifics you will find lots of good info here, plus answers backed by lots of experience.

The same will be said when you begin to question alloys, and again you need to get into specifics for the best answers.:cbpour:

Recently I heard of a fellow who claims that pure lead is all that is needed for most cast bullet shooting, which goes against most advice, but then this fellow goes on to prove his point.

However, this fellow is one of those obsessive type people who is never satisfied until he knows everything there is to know about any subject he takes an intrest in. He takes things waaaaaaaaaay beyond where most folk find workable answers, and then a bit farther.

If you will give those of us on the forum some solid specifics as to firearm, and your use - hunting/target etc. - of the firearm you will get back some solid info.

Keep em coming!

Crusty Deary Ol'Coot

[JIMinPHX]

There are more exceptions to that questions than rules to have exceptions for, but to give you somewhere to start -

Generally pistol boolits don't need gas checks unless you plan to load them REALLY hot. Generally, rifle boolits do need them unless you load them rather lite. Sometimes a gas check will cover for problems with other aspects of your cast boolit loading. Gas checks almost never cause any problems, but they increase the price of your boolits nearly twofold.

[RobS]

+1 on what JIMinPHX said.

[qajaq59]

I use them for all of my rifles. Never bothered with them for the pistols though.

[44man]

I have a different opinion for gas checks because I got old growing up around them.
They were designed to halt skidding at the boolit base when soft lead was popular. There has never been a need to protect the base itself from powder, it will not melt.
Punch a soft boolit too fast with fast powder and even the gas check can fail, skid and gas will leak past it. Final velocity has NOTHING to do with it. Even 750 fps can ruin a boolit.
As the lead we use got harder there was less of a need for the thing and most guns do not need them until you have a problem.
It is and will always be up to the shooter and the alloy he uses for the determination of whether a check is needed.
Shoot a rifle past what lead can take, then the check is needed but there is still a limit to where a jacketed is best.
Some handguns can exceed what lead alloy itself can take.
The base of a boolit should never have rifling marks wider then the actual bore dimensions. If it does, even with a gas check, harden the lead and if you insist on faster, go to jacketed bullets.
This is my simple unbiased answer.

[44man]

Anyone shooting revolvers with pure lead with any powder or velocity has to show what they get and also what the inside and outside of the guns look like.
Not to include BP of course.

[JIMinPHX]

There has never been a need to protect the base itself from powder, it will not melt.


I think that is true in many cases, but not all. When I load H-110 under a plain base boolit, I get some pretty bad cratering on the boolit base. I think that this is caused by the powder granules burning into the base. Most powders don't do this, but some do.

Post #40 on this thread shows what I am talking about -
http://castboolits.gunloads.com/showthread.php?t=41033&highlight=H-110&page=2

By the way,
that thread has several pages of gas check info if you want to spend some time reading.

[TonyT]

The only time I used gascheked bullets was in a Winchester Model 1873 in 32-20 which had a less than shiny bore. The gas checked bullets grouped very well while the plain based bullets did not.

[Bass Ackward]

GCs are almost a dirty word round here. It is considered macho to shoot nothing but PB. Since all my lead is free, I use'em and wear my T-Shirt proudly.

Funny thing is that if you want to get a group buy going on GCs, the order runs up into the millions. That was no typo .... millions. So I guess I am not alone. Actions speak louder than words.

This is rough and to the point. You won't find it stated any better or plainer than this. Copied from the LBT WEB site:

http://lbtmoulds.com/selectbullet.shtml




GASCHECK OR PLAINBASE? – We recommend gas checks without reservation under the following conditions:

If velocities will exceed 1400 to 1600 fps, or estimated chamber pressure will exceed about 35,000/40,000 psi.

For velocities over 1000 fps if shooting sequence will be rapid enough to heat the barrel till uncomfortable for the hands, and especially so if atmosphere temperatures will exceed 90 deg F.

In revolvers with notably misaligned cylinder throats. (Translation almost all revolvers!!!)

In almost all new handguns which haven’t had the bore smoothed by lapping. (Extensive jacketed bullets use helps smooth a little.)

For anyone who shoots so little that GC cost isn’t a concern, and especially so for beginners with loading cast bullets.

Whenever optimum accuracy, and, or, ease of load development takes precedence over slight higher cost and production effort.

When desirable to use one bullet and load in several guns of the same caliber.



GCs:

1. Allow you to use cheaper lubes.
2. Softer lead that is cheaper.
3. Faster powders that are cheaper per shot.
4. You don't bell brass as much so you get more shots from each case, (cheaper)
5. Saves on brushes, patches, cleaning supplies.

Are you seeing a trend here? :grin:

[runfiverun]

GASCHECK OR PLAINBASE? – We recommend gas checks without reservation under the following conditions:

If velocities will exceed 1400 to 1600 fps, or estimated chamber pressure will exceed about 35,000/40,000 psi.

says it all right there for me.

[Mk42gunner]

GASCHECK OR PLAINBASE? – We recommend gas checks without reservation under the following conditions:

If velocities will exceed 1400 to 1600 fps, or estimated chamber pressure will exceed about 35,000/40,000 psi.

says it all right there for me.

That is pretty much what I do. Never saw in so few words though.


Robert

[44man]

I think that is true in many cases, but not all. When I load H-110 under a plain base boolit, I get some pretty bad cratering on the boolit base. I think that this is caused by the powder granules burning into the base. Most powders don't do this, but some do.

Post #40 on this thread shows what I am talking about -
http://castboolits.gunloads.com/showthread.php?t=41033&highlight=H-110&page=2

By the way,
that thread has several pages of gas check info if you want to spend some time reading.
I call that sandblasting from ball powder on lead too soft, not melted. That is the same thing that happens to the edges of the forcing cone. The particles just hit hard.
Here is a base shot with a full charge of 296, ignore the sprue divot, I do! :veryconfu

[44man]

Bass and Veral Smith are correct however I am shooting PB from my 45-70 BFR well over 1600 fps with accuracy good enough to hit 1" targets at 100 yards BUT, pressure is under 30,000 psi so I have no boolit skid.
That little thing is still there to prevent skid past the base. Be assured, punch it too hard and fast or use lead too soft and it will also skid.
I have gone to PB in every revolver all the way to the .500 Linebaugh by just using the correct alloys.

[303Guy]

I think that this is caused by the powder granules burning into the base. Most powders don't do this, but some do.I've seen the 'peening' or the effect of powder kernals being impressed into the base of PB boolits but the above statement could do with some more exploration. Do the powder granules actually get imbedded into the boolit base then burn thus leaving a 'burn scar'? Interesting thing happen to the base of a boolit duting firing. Have a look at this one. It started out flat with just a small rebate - I'm talking machined flat and machined rebate!

http://i388.photobucket.com/albums/oo327/303Guy/BaseCupping.jpg

See how the base has cupped and the rebated edge has tapered into a 'boat tail'. That's where a gas check comes into play. I want this thing to work without one so I'll just keep trying! (Notice this boolit has more rifling impressions up front that at the rear? Not possible!)

[JIMinPHX]

I call that sandblasting from ball powder on lead too soft, not melted. That is the same thing that happens to the edges of the forcing cone. The particles just hit hard.


That's an interesting take on what I saw. I'll have to try some harder alloy with my H-110 load & see what happens.

I'm not sure what you are talking about on the forcing cone. Are you saying that ball powders damage the forcing cone? Are you saying that they sandblast it & leave a rough finish?

[MtGun44]

I find no need for GCs in pistols, including max power loads in .357 and .44 mag.

For me they are almost mandatory for rifles. Almost.

I tend to agree with the 1600 fps velocity limit for PB. I go over it almost every time
in the rifle and never with the pistols.

Bill

[44man]

That's an interesting take on what I saw. I'll have to try some harder alloy with my H-110 load & see what happens.

I'm not sure what you are talking about on the forcing cone. Are you saying that ball powders damage the forcing cone? Are you saying that they sandblast it & leave a rough finish?
Yes but all powders can do it. Ball powders are not only to blame. Slower powder that has not burned yet still hits the forcing cone. Stick or flake powders are easier on the steel.
My SBH has seen nothing but 296 for IHMSA and hunting and has eroded edges on the cone. It has around 60,000 rounds through it and still will do 3/4" at 50 yards without spitting anything from the gap.
Don't be concerned. I didn't mean to scare you!

[Lead Fred]

I dont use them in the 45-70 because my FPS is 1200-1700, and no faster.

I do use them with my 30 cal mold, because they are doing 2200-2500+ fps.

[44man]

I've seen the 'peening' or the effect of powder kernals being impressed into the base of PB boolits but the above statement could do with some more exploration. Do the powder granules actually get imbedded into the boolit base then burn thus leaving a 'burn scar'? Interesting thing happen to the base of a boolit duting firing. Have a look at this one. It started out flat with just a small rebate - I'm talking machined flat and machined rebate!

http://i388.photobucket.com/albums/oo327/303Guy/BaseCupping.jpg

See how the base has cupped and the rebated edge has tapered into a 'boat tail'. That's where a gas check comes into play. I want this thing to work without one so I'll just keep trying! (Notice this boolit has more rifling impressions up front that at the rear? Not possible!)
That boolit is just too soft. Pressure deformation and skidding. A gas check will not help much, only a little. I have seen gas checked boolits that were too soft, cupped in like that too. When they do that, the check can shed when shot.
You seem to have a lot of fun trying to shoot soft boolits! :veryconfu Sorry, I can't tell you how to make it work.

[JIMinPHX]

303 guy, what are you making your boolits out of? Gold? I've never seen recovered cast boolits that color before.

[303Guy]

what are you making your boolits out of? Gold?Wifes been complaining od her jewelry going missing!:mrgreen:

It's my camera and its auto colour that has difficulty in certain light.

I'm doing a thread on this boolit and problem I'm trying to solve.

[runfiverun]

many of the bases could just as easily have the spattered look from the primer......

[JIMinPHX]

If your camera is throwing off the color balance like that, see what type of ambient light it is set for. It might be set to "tungston" or something like that.

[Wally]

In my Magnum pistols (.357/.41/.44 Mag) using std weight bullets and velocities of 1,100 FPS+.. I have found that gas checked bullets are always more accurate than plain base. I didn't believe this until I bought a no. of Freechex tools and then tried them out... Also, one can use them on plain base bullets if you reverse the GC..a bit tricky to insert into the case mouth..but it works beautifully.

[a.squibload]

Wally, if the GC is "cup down" and works fine:

1. seems it would act more like a skirt on a pump to seal the bore,

2. maybe GCs don't really help drive the boolit to prevent skidding,
as the boolit is fully engraved by the time the check hits the rifling,
and upside-down there is no rotational effect on the boolit (GC not crimped on).

3. Maybe I don't have to duplicate my moulds with GC models! Might give it a try sometime, thanks.


Just thought, if they're not crimped on they might be recoverable from a short way downrange!