Form 1 blast chamber dimensions

[1168]

How much blast chamber volume is right?

I’m penciling out a form 1 9mm can (1.375” OD) to be used primarily on a 9mm AR. So, I’ll not need a booster. I think I understand a smaller volume blast chamber reduces first round pop, and a larger one reduces blowback. I’m thinking blowback will be a non-issue, because I have all the leeway in the baffle design. I can make the blast chamber however small I choose, so I’m trying to figure out how small is TOO small. There must be a point at which it does not work right.

Is there a formula for this somewhere?

[tibis3383]

How much blast chamber volume is right?

I’m penciling out a form 1 9mm can (1.375” OD) to be used primarily on a 9mm AR. So, I’ll not need a booster. I think I understand a smaller volume blast chamber reduces first round pop, and a larger one reduces blowback. I’m thinking blowback will be a non-issue, because I have all the leeway in the baffle design. I can make the blast chamber however small I choose, so I’m trying to figure out how small is TOO small. There must be a point at which it does not work right.

Is there a formula for this somewhere?

Depends on how you plan to attach to the host. If using a muzzle device get the tip of the first baffle .15-.20” off of the tip of the muzzle device. I haven’t made direct thread cans for 9mm carbine but limit the size of the BC as much as possible to decrease frp.

[1168]

Depends on how you plan to attach to the host. If using a muzzle device get the tip of the first baffle .15-.20” off of the tip of the muzzle device. I haven’t made direct thread cans for 9mm carbine but limit the size of the BC as much as possible to decrease frp.

Roger, thanks.