While trying to find out what threads to cut for two muzzle breaks, I found a world of different information on line. It seems that there are no real standards for threading barrels of a certain caliper. I happened upon a blog post from the Silencer Shop that really helped. The bulk of the information below – like 95+% – is from that post and I will put the original link below. I have added some additional info and detail that I found on.45, .308, and .300 AAC BLK. I did not include any .50 BMG info. Please refer to your manufacturer, as it seems each has their own preference
I hope that this will serve as a reference for quickly locating how your barrel could possibly be threaded or what threads you need to cut/have cut on your existing barrel. Remember, however, that just because your weapon might be threaded a certain way from the manufacturer – that will not necessarily apply if you have an after-market barrel or have had the barrel threaded yourself. I will include links to thread pitch gauges and thread adaptors below as well.
- M=Metric (for example – M13.5×1 LH means that the numbers are metric instead of standard.)
- LH=Left Hand (for example – M13.5×1 LH means the threads are backwards from what you typically expect. This thread pitch would require righty-loosey, lefty-tighty…)
- RH=Right Hand (for example – M16x1RH means the threads work how you typically expect (righty-tighty…). If there is no LH or RH designation – RH is the default.)
Common Threading:
.22 LR, .22 MAG, .17 HMR
- The standard thread for these calibers is 1/2×28. Please let us know if you are aware of any notable exceptions.
9mm
- 1/2×28 is the most common thread for 9mm weapons – both carbine and pistol. However, there is no universal standard and some 9mm carbines come with a 1/2×36
- H&K weapons use the M13.5×1 LH thread pitch
- Sig Sauer weapons use the M13.5x1LH thread pitch
- Lone Wolf and SilencerCo replacement barrels for the Glock 17 and 9mm barrels are 1/2×28
.40 S&W
- 9/16×24 is the most common thread pitch for .40 cal weapons.
- H&K weapons use the M14.5×1 LH thread pitch
.45 ACP
- .578×28 is the most common thread for .45 cal weapons, especially 1911 pistol barrels.
- Lone Wolf and SilencerCo replacement barrels for the Glock 21 are .578×28
- H&K USP Tactical uses the M16x1 LH thread pitch
- H&K Mark 23 (Socom) uses the M16x1 RH thread pitch
5.56mm (.223)
- AR-15s use the 1/2×28 thread pitch
- Steyr Aug uses the M13x1 LH thread pitch
- H&K weapons use the M15x1 thread pitch
- Ruger Mini uses 9/16×24 thread pitch
.300 AAC BLK
- .300 Blackout barrels that are “usually” threaded 5/8-24. You can use an adapter that changes the thread pitch to 1/2-36 so you can use 9mm silencers when shooting SUBSONIC ammo.
7.62mm (.308)
- 5/8×24 is the most common thread for 7.62mm/.308 weapons
- If you have a rifle with a spotter barrel, like a Savage Axis, then it needs to be cut 1/2×28 due to barrel diameter.
- Sako TRG uses the M18x1 thread pitch
- Accuracy International uses the M18x1.5 thread pitch
- AK-47/74 &SKSs (7.62X39) use the M14x1LH thread pitch
.338LM
- 5/8×24 is the most common thread for .338LM weapons
- Sako TRG uses the M18x1 thread pitch
- Accuracy International uses the M18x1.5 thread pitch
- Desert Tactical Arms uses the 3/4×24 thread pitch