Posted: 4/10/2015 9:24:17 PM EDT
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How do you fix threads that are not concentric to the bore of a rifle? I have a Draco that I form 1'd to an SBR. The threads aint quite right. I'm about to do a form 1 7.62 can. I want to be able to use a can on my AK. Would you just thread a sleave on the existing threads and then thread it to something like standard threads? 5/8x24 for example? |
I was tired last night, I shoulda knew that 
14mm is the OD (major diameter) so .551" at max, should be slightly less than that. Thread minor (bottom of thread) for a 5/8-24 is .580-.587. I wouldn't have any issue with that. I doubt your current threads are .020 off center. |
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Quoted: I was tired last night, I shoulda knew that 14mm is the OD (major diameter) so .551" at max, should be slightly less than that. Thread minor (bottom of thread) for a 5/8-24 is .580-.587. I wouldn't have any issue with that. I doubt your current threads are .020 off center. |
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Never, ever trust the factory threads on an AK for suppressor use!
They cannot be trusted for concentricity nor axial alignment. They also in no way come close to Class III thread fit, which the majority of manufacturers call out on their thread specs. I will thread and sweat on an oversized bushing, set it up in the lathe zeroing in on the bore centerline. That way we have assurance of concentricity and axial alignment. Turn and thread bushing as normal. I have done them in 9/16" and 5/8" threads this way with good results. The added bonus is with the bushing we now have an adequate shoulder for the suppressor to register on. All without pulling the barrel. |
| Is a class 3 fit really necessary when it's going up against a shoulder? I guess a couple thou of slack in the threads could throw the suppressor off center,but if the shoulder is square the suppressor should also be square. What's the exit hole diameter on a 7.62 can anyways? |
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Quoted: Is the bbl long enough to just cut the threads off and put proper ones on? A threaded collar can work if done well but it's not as good as doing them correctly. |
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Quoted:
Is a class 3 fit really necessary when it's going up against a shoulder? I guess a couple thou of slack in the threads could throw the suppressor off center,but if the shoulder is square the suppressor should also be square. What's the exit hole diameter on a 7.62 can anyways? Is a Class III fit necessary? If that's what the manufacturer calls out then yes, it is necessary. Most suppressors register on the threads and the shoulder so they must be correct and perpendicular to the BORE, not the barrel. The correct threads are also critical if an issue is encountered, most manufacturers warranties are voided if the threads are not to their specifications. CommBloc stuff is notorious for being non concentric relative to the barrel diameter. It would not be such a big deal if the barrels were larger diameter so you have some fudge factor and material to work with but they don't leave much. You need to do this right, you don't have much room for error. A .002 error at the muzzle will equate to about .020 with a 10" suppressor which is more than enough for a strike. Not sure on end cap hole size, I would guess .030-.040 over bore diameter. |