GC behind case neck

[jdfoxinc]

I have read several posts mentioning GC behind case neck, .357Sig, 7.62x39, 5.45x39, etc. As though this "Is a had thing". Having the bullet take up usually empty spade has been proven to raise chamber pressure. (A.357Sig loaded with any 124gr bullet j-word of lead has that condition.) So other than increased pressure what is bad about having GC behind the neck? Scientific evidence would be appreciated.

[BK7saum]

The main concerns are that it would come off in the case and then be left in the barrel as a barrel obstruction upon firing another cartridge.

[MostlyLeverGuns]

It is common to have the gas check below the case neck in several common calibers using longer bullets. 300 Savage, 308 Winchester, others - not a problem with properly applied/fitted gas checks. With 'small' capacity cases concern for seating depth affecting case capacity substantially is the issue. Whether plain-base, gas-check or jacketed, it is the reduction of case capacity due to seating depth that must be watched.

[MT Chambers]

I am required to do this many times as the bullet will not enter the bore unless seated deeper, deep enough to be below the shoulder, some of my most accurate loads have the gc well below the case's shoulder. I'm sure that all that pressure on firing would blow any gc out the barrel, but it is that pressure that will keep the gc in place at least until it exits the muzzle.

[Soundguy]

It is common to have the gas check below the case neck in several common calibers using longer bullets. 300 Savage, 308 Winchester, others - not a problem with properly applied/fitted gas checks. With 'small' capacity cases concern for seating depth affecting case capacity substantially is the issue. Whether plain-base, gas-check or jacketed, it is the reduction of case capacity due to seating depth that must be watched.

Agreed, on my 35 REM, the gas check top is at or just under the area of the case neck hitting the shoulder.

[Lloyd Smale]

as long as its a crimp on check. I don't think id want to use something like a non crimping aluminum check down that could fall off down it the powder space.

[Shiloh]

Do the fit and are they on secure?? That is the concern.
I don't need to worry with what I load.

Shiloh

[dragon813gt]

You're not going to find scientific data. What you will find is a lot of "what ifs". If you load for the 300 Savage the gas check is going to be below the neck. Make sure it's crimped on well and you won't have any issues.

[1trkmind]

i use vulcan gas checks and they shave lead and have a tendency to fall off. Anyone know how yo fix that? Is that what a G C expander for?

[Shiloh]

I got a sample of Vulcan check. Looked promising but the fall off. My Gator checks are more money but they stay on. I have found my bolts in the berm with the check still on. I also find flattened checks around where I nail the gong.

SHiloh

[sharps4590]

I've often wondered the same thing, about gas checks below the case neck but, always in rifles. I'm very inclined to agree with those who say if the check is firmly crimped it's a non-issue as I have a few rifle loads where the base of the bullet protrudes below the neck/shoulder junction. Never has there been a problem nor do I anticipate any. However, I have never gotten to the point where the thought doesn't cross my mind.

[popper]

A few years back a gent said he didn't crimp GC on the boolit. IIRC it was for 06 & he used Lee loader. Shot one and looked in the bore and sure enough, GC was in the bore. I try at minimum to keep the top of the GC in the neck. At least it won't catch the edge on the shoulder junction. As an aside, L.G. & G.S noticed problems with GCs. Larry used lino and had GC coming off down range. Tim noticed the GC shank was smaller in dia. on recovered boolits. Larry switched to #2 and problem solved. IMHO, both these phenomenon are related to the strength of the alloy. Strength is measures as tensile (stretching), compression ( bending) shear ( twisting) and impact ( pressure heating). When shot, the base under the GC plasticizes and flows (bumping) locking onto the GC tighter. Momentum of the boolit (forward of the GC) & lesser friction of the now softer Pb causes stretching at the base, Cu friction is greater. Pb swages down to bore size much easier than the GC so additional force trying to pull the GC off. In Larry's case, the harder alloy didn't 'flow' enough, just enough to stretch. Seems this applies to the 'apparent' increased accuracy or bore-rider designs. tests show there is a torque softening of Pb alloys (rifling groove is wider at the nose), but bore rider is swaged/bumped into the rifling vs being sliced. Slicing creates more torque/distortion of the boolit. Like solid core solder, bending takes more to break it than twisting. Further evidence on the single GC I've recovered had no boolit, just a shiny silvery (melted looking) ring on the inside edge of the GC. It was a hard alloy. The boolit probably disintegrated when cutting through 12 AWG steel wire. Anyway, when I use a GC, I don't want high pressure to 'see' any Pb.

[Texas by God]

You're not going to find scientific data. What you will find is a lot of "what ifs". If you load for the 300 Savage the gas check is going to be below the neck. Make sure it's crimped on well and you won't have any issues.
This mirrors my .300 Savage experience. #2 alloy crimp on Hornady checks. Nary a problem in a recoil operated Model 81 Remington. Best, Thomas.

[sharps4590]

Very interesting food for thought popper. Thank you.