adelbridge
Member
Is there a standard thread pitch for an AR-15 7.62X39 barrel? Most everything I am seeing in 1/2X36.
AR Barrel in 7.62X39
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rbernie
Contributing Member
There is no paper standard.
It used to be that they'd be all the same pitch as 308-class AR's (5/8"x24 TPI) to keep folk from accidentally screwing on one intended for smaller calibers (5.56) that used 1/2"x28 TPI. The 5/8" muzzle diameter also provided a certain wall thickness that was considered necessary, whereas the 1/2" muzzle diameter was considered awfully thin in the wall for comfort.
In the last handful of years, most of that discipline has apparently been lost. M1S was the first that I saw that deviated from that de-facto standard, back in the early/mid 2000s. Now is seems that many in industry are moving to 1/2"x36 TPI as the catch-all for chamberings over 22 caliber. I suspect it's to help address the current trend back towards thin/light barrels.
For my own purposes, I still tend to use barrels that support the 5/8" thread diameter for my 30cal rifles, and use barrels that support the 1/2" thread diameter for my 6.8 and below chamberings. My Shaw 7.62x39 and 300 AAC barrels have all been 1/2".
It used to be that they'd be all the same pitch as 308-class AR's (5/8"x24 TPI) to keep folk from accidentally screwing on one intended for smaller calibers (5.56) that used 1/2"x28 TPI. The 5/8" muzzle diameter also provided a certain wall thickness that was considered necessary, whereas the 1/2" muzzle diameter was considered awfully thin in the wall for comfort.
In the last handful of years, most of that discipline has apparently been lost. M1S was the first that I saw that deviated from that de-facto standard, back in the early/mid 2000s. Now is seems that many in industry are moving to 1/2"x36 TPI as the catch-all for chamberings over 22 caliber. I suspect it's to help address the current trend back towards thin/light barrels.
For my own purposes, I still tend to use barrels that support the 5/8" thread diameter for my 30cal rifles, and use barrels that support the 1/2" thread diameter for my 6.8 and below chamberings. My Shaw 7.62x39 and 300 AAC barrels have all been 1/2".
adelbridge
Member
Found and bought my 7.62x39 barrel in 5/8x24 problem averted
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