muzzle brake thread size

[ballistic64]

For a barrel with a .830 muzzle diameter (30 cal), which brake thread size would be best, 5/8 or 3/4 ?

 

[jrm850]

Which brake are you using? If it is a bigger OD and you don't mind a steeper transition, I would go with the .750. If it is muzzle diameter, a .040" residual wall would be pretty thin. I would probably put the thin wall on my gun if it was just a range queen, but not a customers.

my reasoning- If the brake was made from 416, the sectioned area of that thin wall would equate to about .1^2", or about 10k pounds of force to pull apart assuming the tension was applied exactly axially. Plenty of strength for the application under perfect conditions; a safety factor of 2 easily attained. However, a drop on the muzzle could put you out of business or worse if you pulled the trigger on a bent brake.

There was a recent topic on this board about muzzle IDs opening up when cut for brakes or cans. It makes a good case for cutting the least amount of material possible around the muzzle.

 

[ballistic64]

I'm going to use a JP eliminator.The barrel blank I have coming is a Rem varmint contour with a muzzle dia. of .830 at 26". This barrel is going to be cut down to 20", as it is going on a Model7. So the actual muzzle dia. will probably larger than the .830 at 26". Not sure by how much yet, I should have the barrel this week.

 

[IdahoCTD]

You can get away with 3/4x24 since your shoulder diameter will be .850"+ at 20" but I still wouldn't try to turn a brake to that diameter with 3/4x24 threads. .050" per side in a baffled brake is too thin.