Gas Checks

[Henry Haina]

Requesting pros and cons on copper v aluminum for gas checks. Concerned on barrel life related to each material. Seeking best accuracy and velocity. I have a tendency to want more velocity. I will be using this in 458 WM, 44 Rem Mag, 338 WM, 270 Win, and 25-06.

 

[groper]

Well i cant say im speaking from experience, but i will say the following;

1. Aluminium has a much lower hardness than copper, copper is brinell 874Mpa whereas Aluminium is 245Mpa. The hardness of a material is directly related to its ability to be scratched or worn by other materials in contact with it. Therefore, aluminium would allow for considerably longer barrel life (in theory)

2. Aluminium has a shear modulus of 26Gpa whereas copper is 48Gpa. Therefore the ability of the gas checks to remain intact and not fail is reduced, therefore the gas checks would have to be thicker in order to withstand the same force. Not twice as thick as the strength of a material is propotional to the thickness squared. So you would need about 1.5times thicker in aluminium to ahcieve the same gas seal strength and resistance to stripping in the rifling.

3. If your considering using aluminium in projectiles, you would also have to consider the melting point vs heat generated from friction and propellant. Aluminium may not withstand the heat but it would depend on the caliber, speed, barrel length etc... AL would probably be fine in a pistol application where velocity is low, but from a high powered rifle it most likely would cause some melting of the gas checks where there is highest pressure and friction in contact with the lands... the seal may leak (maybe?). Whether this would be significant or inconsequential, i dont know...

How about some more info on what your doing?

 

[Trickymissfit]

I shoot a lot of cast lead bullets in my revolvers, and I also use a gas check in my 44 mags (250 grain Keith style with a gas check). Round seems to work OK, but will confess that I've never compaired it to a similar bullet without one. When I started using them in my two 44 mags I was told that they might affect the group size. I can shoot sub 3" groups off a rest at 50 yards with a revolver. Leading seems tobe minimal (1380 fps), and for what it does it's a nice hunting / plinking load. But in my T/C's I shoot a lot of hot H110 loads, and it dosn't work quite as well. I get a leading of the barrel after about eight rounds ( about 1750 fps), but still a great hunting load
gary

 

[Kevin Thomas]

"I have a tendency to want more velocity."

Now THERE's an understatement if I've ever heard one!