M14 Forum

CNelson

Please forgive my ignorance. I have a question regarding re-threading of the outer diameter of an m-14 barrel. Knowing that the standard thread at the flash hider is .595 and that the diameter between the gas cylinder lock and the step up for the flash hider is .590...

If an M-14 barrel were to be cut down to 20in in length could it be possible to thread the outer diameter to use flash hiders or muzzle breaks that are threaded in m15x1?

MemphisMachinists

This area between the gas cyl and flash hider is an undercut and I have found that the size will vary considerably here. You can get away with threading diameters that are smaller than the actual size. If I understand you correctly you are saying you have a barrel that is 15 MM in the area that you want to thread. If this is the case or even if it is 5 thousandths or so under you can still thread it. Just don't bring your threads to a point. If you have a thread micrometer or thread guage wires you can measure you root or the bottom of the thread. the easiest way to do it is to have the part you want to screw on in hand when threading and just try it as you are geting close.

I guess the short answer is yes. Sorry for rambling, but it is easy to misunderstand a situation. Don't trust a drawing dimension. Trust your mike.

CNelson

Between the step down between the gas cylinder all the way up to where the splines and thread for the flash hider are machined the barrel measures .590in diameter or 14.986mm. Which means I am approx 0.00055in or 0.014mm undersized for standard metric thread of M 15x1 which has a outer thread height of 15mm and the threads are cut deeper. If I cut those threads is that difference big enough to give me muzzlebrake alignment issue or where it will work loose?

MemphisMachinists

No