BLR w/Muzzle Brake Wall Thickness

[mhotz]

Hello

I have a question about the minimum safe wall thickness for a Browning BLR with a muizzle brake installed.

I purchased a used Browning BLR in 300 WSM.The rifle has a pencil barrel (OD approx = .6" at muzzle). It came with a KDF muzzle brake (.6" OD, 1/2-28 Threads) already attached.

My undedrstanding is that a common rule-of-thumb states that to be safe a barrel should have a minimum of .140" wall thickness remaining after threading the barrel for the brake.

Therefore, this rifle's .05" wall thickness [ (.6 - .5)/2 = .05 ] after threading for the KDF is 64% less then the rule-of-thumb of .140".

What are your thoughts? Is the rule-of-thumb bogus? Has anyone seen first hard or heard about a BLR in .308 caliber with a muzzle brake having a problem because of wall thickness?

Thanks

(This question also posted on The Firing Line forum)

[ar15barrels]

I purchased a used Browning BLR in 300 WSM.The rifle has a pencil barrel (OD approx = .6" at muzzle). It came with a KDF muzzle brake (.6" OD, 1/2-28 Threads) already attached.

My undedrstanding is that a common rule-of-thumb states that to be safe a barrel should have a minimum of .140" wall thickness remaining after threading the barrel for the brake.

Therefore, this rifle's .05" wall thickness [ (.6 - .5)/2 = .05 ] after threading for the KDF is 64% less then the rule-of-thumb of .140".

Your method of calculation of barrel wall thickness is incorrect.
Your 0.6" and 0.5" dimensions have to do with the barrel SHOULDER height behind the muzzle brake.

1/2-28 threads have a 0.440" ID and the bore is 0.3" so you have a 0.070" barrel wall thickness under the threads.
(0.440-0.3)/2=0.070" barrel wall thickness.

1/2-28 threads are FINE on the MUZZLE of a 30 caliber barrel.
That 0.140" barrel wall thickness would be more important within the first 8" of the chamber where pressure is highest.
After that, you can go thinner as the pressure is MUCH lower.

[kcstott]

What Randal said and here's a link to engineered dimensions

CIP material and pressure standards