Should I try to fix muzzle shoulder parallelism

[Arizona_Mike]

Just got my third suppressor (silencer) yesterday. So far every one mounted on a 2 Ruger, a Colt, an Adco, and several Lone Wolf barrels has been right on as far as concentricity (checked with land-diameter polished drill rods). Last night I found my AAC Cyclone was right on with a Colt barrel, a little off with my AR Stoner 300 BLK barrel (but nowhere close enough to cause a baffle strike) and to my surprise, a little further off (but still safe) with my S&W M&P10 barrel.

Should I take a few licks with sanding block on the high side of the barrel shoulder? 0.001 at the shoulder would equal about 0.013" at the exit of the suppressor.

Mike

 

[wally]

Should I take a few licks with sanding block on the high side of the barrel shoulder? 0.001 at the shoulder would equal about 0.013" at the exit of the suppressor.

If your other can is fine on these barrels then I'd think it wasn't the barrel. I'd be talking to AAC instead.

0.001 at the shoulder would equal about 0.013" at the exit of the suppressor

which is why you could end up like the guy trying to take the wobble out of a table by taking a little off the other three legs.

Have you done a through FOD check of the shoulder, threads and suppressor face? As you know it doesn't take much, an "average" hair is about 0.001" diameter.

 

[Arizona_Mike]

Yes on the FOD check.

As I said, the Cyclone is right on with the Colt barrel (with Gemtech subcaliber adapter). I can also try it on my Shilen/Ranier Ultramatch just to be sure.

Mike

 

[wally]

Sounds like the barrels in question can only be checked with the Cyclone. Both suppressors good on the Colt barrel does suggest the other barrels are the issue.

Without a lathe not sure what you can do to "square them up" but another part of concentricity is the bore within the barrel. The shoulder could be square but the bore is not centered in the threads -- can easily end up this way if the threads are cut on a 3-jaw chuck indexing on the OD, which is fine for a flash hider or muzzle brake but could be bad news for a suppressor.

 

[MCMXI]

Some suppressor companies recommend 0.0005 perpendicularity on the shoulder. I wouldn't take a sanding block to it.

 

[Charger442]

if i had reservations about shoulder squareness, like i did with my RRA factory 16" barrel threads, i would have it checked by a competent gunsmith who knows Class III thread specs and is familiar with suppressor mounting.

I've used Tj's Gunsmithing in Aurora CO several times (they were highly recommended by Thunder Beast Arms) and I have been pleased. They fixed the RRA i had and have threaded 2 other barrels for me. I am also going to have them thread a Colt HBAR from the mid 90's before the beginning of the summer.