Converting 22 cal Muzzle Brake to a 9mm. How much should I bore it out to?

[awesomealvin]

Hi Everyone,

Noob question here.

I have a brake in 22 cal (designed for 22LR and 223) that I want to machine out for my 9mm carbine (Ruger PCC). Is there a particular "rule of thumb" as to how much larger the brake's inner diameter should be compared to the bullet? Or is clearance = clearance? I got a mini lathe and boring bar, so a +/-0.005" is easily achievable for me. I also plan to cut down the brake from 3 vents to 1. Less powder, less gas, less vents required...at least that's my theory. What do you guys think?

Thanks

 

[Can-down]

9mm is pretty soft... but if your bored and feel like boring.... Why not check common sizes being produced and go from there?

 

[tiriaq]

20 thou over should be fine. Go for .375".

 

[guntech]

20 thou over should be fine. Go for .375".

Providing you do it concentric to the bore while the brake is attached... or at least concentric to the brake threads while held in the chuck. If you can't do that then open it up another 15 thou...

 

[mac100]

Is your 9mm barrel the same thread size. Most are 1/2-36 but some are 1/2-28 like a223 brake.
I assumed you already threaded by hand on your barrel but just in case I thought I would mention it.

 

[awesomealvin]

Is your 9mm barrel the same thread size. Most are 1/2-36 but some are 1/2-28 like a223 brake.
I assumed you already threaded by hand on your barrel but just in case I thought I would mention it.

It's a 1/2x28 thread. Just a cheap one I got for $15. I'll machine it to 0.375" ish. I still need to setup the lathe, I'll keep you guys posted. Thanks!