Common Barrel Thread References

One question that has always been a mainstay in our most-questions-asked category is whether a specific silencer will fit a specific gun. With threading looking similar, and acronyms being thrown around like hot tamales, we understand your plight. As the suppressor industry grows, it seems thread pitch options have too.

While some thread pitches are more popular than others due to military use or it being made common by specific firearm manufacturers, the last thing you want to happen is to finally get your suppressor in and realize that it doesn’t match up with your host firearm’s threading.

The list that we are providing you is to serve as a reference for quickly locating how your barrel may be threaded. Remember that factory barrel threadings and after market threadings aren’t always the same.

M = Metric (for example - M13.5x1 LH means that the numbers are metric instead of standard)

LH = Left Hand (for example - M13.5x1 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)

TPI = Threads Per Inch

Now that you have your commonly-used threading abbreviations, let’s get into caliber specific threading.

The standard thread for rimfire calibers is 1/2x28.

Many .22LR pistols have barrels that are threaded underneath the slide. Some examples of threading underneath the slide include the Ruger SR, Walther P22, Sig Mosquito, and GSG 1911. Because of the thread location, these pistols require an adapter that will move the threads in front of the slide and allow you to attach a suppressor.

We should also note that some CZ rifles use a 1/2x20 thread pitch. Because of this thread pitch, in order to thread a suppressor onto the CZ rifle, it will require an adapter.

1/2x28 is the most common thread for 9mm weapons - both pistol caliber carbine (PCC) and handgun. There are a few firearms that run different barrel threads.

• H&K weapons use the M13.5x1 LH thread pitch
• Glock weapons use the M13.5x1 LH thread pitch
• Sig Sauer weapons use the M13.5x1LH thread pitch (with an exception of the P320 variants which run New Hampshire made barrels in 1/2x28)
• H&K MP5-N uses the 1/2x30 thread pitch

9/16x24 is the most common thread pitch for .40 cal firearms. Here are the exceptions to the above rule:

• H&K weapons use the M14.5x1 LH thread pitch
• Glock weapons use M14.5x1LH thread pitch
• Sig Sauer weapons use the M13.5x1 LH thread pitch

.578x28 is the most common thread for .45 cal weapons. As you’ve seen, there are always exceptions:

• H&K weapons use the M14.5x1 LH thread pitch
• H&K USP Tactical uses the M16x1 LH thread pitch
• H&K Mark 23 (SOCOM) uses the M16x1 RH thread pitch
• KRISS Vector SMG uses the M16x1 LH thread pitch
• Glock weapons use the M16x1 LH thread pitch
• Sig Sauer P220 uses the .578”x28 thread pitch

AR-15s generally use the 1/2x28 thread pitch, but there are a few that do not:

• H&K weapons use the M15x1 thread pitch
• Ruger Mini uses 9/16x24 thread pitch
• Steyr Aug uses the M13x1 LH thread pitch

5/8x24 is by far the most common threading for 7.62mm/.308 weapons, but here are a few exceptions:

• Accuracy International uses the M18x1.5 thread pitch
• Sako TRG uses the M18x1 thread pitch
• FN SCAR 17 uses 5/8x24 thread pitch
• AK-47s use a number of different thread pitches
• The most common thread pitch for eastern European and most US made weapons is M14x1 LH

5/8x24 is the most common thread for .338LM firearms. A few exceptions are:

• Accuracy International uses the M18x1.5 thread pitch
• Barrett MRAD uses the 3/4x24 thread pitch
• Desert Tactical Arms uses the 3/4x24 thread pitch
• Nemo Omen (.300 Win Mag) uses the 5/8x24 thread pitch
• Sako TRG uses the M18x1 thread pitch

For AK’s, there are two thread pitches that are used most commonly. AK’s are unique in that these rifles are threaded on the gas/sight block, not the barrel:

• M24x1.5 RH - This thread pitch is most often found on the gas/front sight block of AK-74 rifles
• M26x1.5 LH - A somewhat unique pitch that can be found on PAP92 or M85 Yugo builds

For 50 cal firearms, it largely depends on the manufacturer, but two thread pitches used more often than others:

• Armalite AR50 uses the 1” x 14 TPI
• Barrett uses the ⅞” x 14 TPI
• EDM uses the ⅞” x 14 TPI
• McMillian TAC-50 uses the 1” x 14 TPI

We’ve just given you a comprehensive list of common thread pitches, but we always recommend checking with the manufacturer of whatever you’re trying to suppress. Check twice, buy once!

Note: This post was originally published September 16, 2011, and has been updated for freshness and comprehensiveness.

Additional Resources:

How to Buy a Silencer

Buy a Silencer - A Client's Journey

How to Sell a Silencer

The Good, The Bad, and The Ugly