Chances of GC coming off inside case?

[Bazoo]

I think a GC could come off in the case in a revolver if you didn't have a good crimp. I say this having pulled bullets with a kinetic puller and having the GC stay stuck in the case.

When fired, the expanding gas pushes against the gas check. That would keep even a loose check in place down the bore.

[Peregrine]

I've found a gas check inside a fired .308 case, didn't realize it was still in there until I encountered a case that was unusually hard to decap and upon closer inspection found the GC still inside with a hole punched through it.

I often have to seat boolits with the gas check below the neck but this was a load where I considered the base of the boolit high enough in the neck to prevent the gas check from coming off. So much for that.

I consistantly have issues with gas checks that come off in flight. Well, they don't actually cause any issues but there is evidence to suggest they are coming off. Alloy too hard and boolit casting slightly too large, I believe.

[2manyguns]

I consistantly have issues with gas checks that come off in flight. Well, they don't actually cause any issues but there is evidence to suggest they are coming off. Alloy too hard and boolit casting slightly too large, I believe.[/QUOTE]
///////do you think it makes a difference if the GC comes off after the bullet is out of the pipe ?/////

[Larry Gibson]

I consistantly have issues with gas checks that come off in flight. Well, they don't actually cause any issues but there is evidence to suggest they are coming off. Alloy too hard and boolit casting slightly too large, I believe.

///////do you think it makes a difference if the GC comes off after the bullet is out of the pipe ?/////[/QUOTE]

I'm sure there are some variables involved but losing a GC in flight can have an adverse affect on accuracy. I've shot a lot of the old original Lyman slip on GCs and quite a few of my own home made ones. In rifles with slower twists shooting at moderate velocities (under 1800 fps) I've watched a lot of bullets out of rifles and handguns go down range with the Sun shining off the GC.....kind of neat to watch. Never really had much problems with those GCs coming off in flight but then all were snug fitting, especially after sizing. Above 1800 fps, especially if the twist is faster than 1-10, I have observed the adverse affect caused when GCs come off. Not only is accuracy adversely affected but severe damage to chronograph screens can also happen.

How adverse the accuracy is affected depends on the range to the target and the RPM. At 100 yards every time the GC came off the shot was a "flyer" out of the group. Even with Crimp on GCs carefully put on the bullets they come off at high RPM and/or high velocity (2000 - 3000+ fps). My experience with aluminum GC made from .012 or .014 stock show they split and come off a lot above 2000 fps in 10 and 12" twist 30 caliber rifles and accuracy always suffers. Those who shoot at lower velocity and at 50 yards probably won't notice any adverse affect.

[2manyguns]

///////do you think it makes a difference if the GC comes off after the bullet is out of the pipe ?/////

I'm sure there are some variables involved but losing a GC in flight can have an adverse affect on accuracy. I've shot a lot of the old original Lyman slip on GCs and quite a few of my own home made ones. In rifles with slower twists shooting at moderate velocities (under 1800 fps) I've watched a lot of bullets out of rifles and handguns go down range with the Sun shining off the GC.....kind of neat to watch. Never really had much problems with those GCs coming off in flight but then all were snug fitting, especially after sizing. Above 1800 fps, especially if the twist is faster than 1-10, I have observed the adverse affect caused when GCs come off. Not only is accuracy adversely affected but severe damage to chronograph screens can also happen.

How adverse the accuracy is affected depends on the range to the target and the RPM. At 100 yards every time the GC came off the shot was a "flyer" out of the group. Even with Crimp on GCs carefully put on the bullets they come off at high RPM and/or high velocity (2000 - 3000+ fps). My experience with aluminum GC made from .012 or .014 stock show they split and come off a lot above 2000 fps in 10 and 12" twist 30 caliber rifles and accuracy always suffers. Those who shoot at lower velocity and at 50 yards probably won't notice any adverse affect.[/QUOTE]

thanks for that info i am only shooting G C with 44 mag rifle with 265&300gn cast so my velocity is quite low and a 300 blk with a 208 gn pill that is even slower

[derek45]

This thread has some good pics of gas checks, not, flying off.

http://castboolits.gunloads.com/show...-the-Lee-310gr

[Larry Gibson]

Here's what GCs coming off at HV can do to screens.....

Attachment 274056
Attachment 274057
Attachment 274058

[Yooper003]

I believe powder coating after crimping on gascheck is good insurance to GC coming off.