Gas checks or not

[catkiller45]

AS you know I have been experimenting with different alloys and smokeless powder as well as the Goex black powder.So know I am looking for some information about the gas checks.

If I decide to continue on in my testing with the smokeless and also STAY within The Muzzle velocitys of black powder,do you feel there is a need to use the gas checks as well?

I know that the BP goes of with a flash effect and that Smokeless is more of a continues burn which may or may not effect the base of the bullet..Only recovery of the bullet will tell if there is gas cutting or not.

Please feel free to pass your comments along.....John

[chunkum]

My notion on the gas checks effects was voiced in another thread by another member recently. He stated and I agree that they serve as much as a "copper" driving band as anything else and give the bullet a better "hold" on the rifling, hence more reilable stabilization. I think protection of the bullet base is a secondary (though still desirable) benefit. Good obturation (read - oversized bullet) remains important.
Best Regards,
chunkum

[sundog]

Lead and copper don't grip the same. A check is not integral part of a boolit, but an add on. Suppose the boolit strips and the check doesn't. sundog

[felix]

Black powder burns significantly cooler than white powder (smokeless). Single base powders (smokeless) burn cooler than double base powders (smokeless). Adding deterrents might or might not add a measurable amount of cooling to the various white powders, but anyhow, the amount won't be significant. The thing to remember here, is that all metals will vaporize when suddenly hit with any flavor of white powder. The amount of vaporization (plazma size particles) is the killer in terms of leading/coppering. Can't avoid it, but getting the boolit sized properly will minimize where that plazma will be deposited. Hopefully, we can get it all placed back where it came from, rather than have it spread into the area within the gun where it can build up, such as in the throat area plus down the bore a bit. But, that is impossible, so we have to clean the guns every once in while for everyday type of shooting. For BR shooting for real, the gun has to be kept immaculate between relays to remain competitive. Obviously, for us on this board this would be carrying things out to the extreme, and not worth the price of the extra (actually, uneven) throat/crown wear caused by stroking the barrel. ... felix

[w30wcf]

catkiller45,

I have shot gas checked bullets sans gas checks with complete satisfaction at velocities in the 1,200-1,400 f.p.s. range. Alloy was w.w.+2% tin.

One example I can recall in particular is the RCBS 150 gr. in the .30-30. Groups at 200 yards were the same with bullets with or without gas checks....and no leading.

Good luck,

w30wcf

[chunkum]

Lead and copper don't grip the same. A check is not integral part of a boolit, but an add on. Suppose the boolit strips and the check doesn't. sundog
It's certainly true that copper and lead have different friction coefficients, the copper having the larger amount of friction on the bore. My notion on this is from personal observations of a small sample of recovered bullets and is hypothetical, just as is your supposition. But since we're speculating, I'd speculate that when the bullet first encounters the rifling, it's not moving as fast as it will be further on down the barrel and not as likely to strip here as further along. The tendancy for the softer (than the copper) alloy to strip at this point would, I'd think, be influenced more by the inertia of the circumference of the bullet, resisting the initiating spin, than any other factors. The gas check, having been swaged on in the sizer, is further tightened on the bullet by the rifling engraving and any constriction that occurs in the throat and bore, making it an even tigher fit. I'd think it unlikely that the bullet could strip from the rifling and the gas check, now "rifling engraved" on its base, in the first part of its travel. Increasing forward speed after this point and the twisting force of the rifling, working against the inertia of the bullet circumference, initiating the spin would seem to be the later influence for any tendancy of the bullet to strip. I can't help but think that, as the driving bands intrinsic in the bullet's design make the "hold" on the rifling more secure, the now tighter gas check on the bulet base is likely to do the same thing.