FIREARM BARREL THREAD PITCHES FOR SILENCER USE
BARREL THREAD PITCHES & SIZES | FIREARM THREADING REFERENCE
Hopefully this reference of common firearm barrel thread pitches and sizes helps answer your questions. It is not comprehensive, and there are exceptions and model-specific variations.
Barrel thread specifications are commonly expressed by thread diameter, thread pitch or threads per inch (TPI), and thread direction. Always verify the manufacturer's specifications for your exact firearm before selecting a suppressor, muzzle device, adapter or other threaded accessory.
A matching thread specification does not by itself guarantee compatibility. Barrel shoulder geometry, bore alignment, caliber rating and the specific mounting system also matter.
UNDERSTANDING THREAD PITCH
Thread pitches are generally expressed in either imperial or metric measurements.
Imperial:
The first number is the thread diameter in inches, followed by the number of threads per inch (TPI). A higher TPI means finer threads, while a lower TPI means coarser threads.
For example, 1/2x28 means a 1/2-inch diameter with 28 threads per inch.
Metric:
Metric threads are identified by an M. The first number is the thread diameter in millimeters, followed by the distance between threads in millimeters.
For example, M18x1 means an 18 mm diameter with a 1 mm thread pitch.
Thread direction may also be specified as RH (right-hand) or LH (left-hand). Right-hand threads tighten clockwise, while left-hand threads tighten counterclockwise.
For example, M13.5x1 LH means a 13.5 mm diameter, a 1 mm thread pitch and left-hand threads.
IMPORTANT ABBREVIATIONS
M = Metric
RH = Right Hand
LH = Left Hand
Unless specifically identified as metric, thread sizes below are expressed in inches.
COMMON FIREARM BARREL THREAD PITCHES
RIMFIRE
.22 LR / .22 WMR / .17 HMR
- 1/2x28
- M8x0.75 RH on some specific models (.22LR
.21 Sharp
- 1/2x28 on current threaded Savage models
PISTOL & REVOLVER CALIBERS
.380 ACP
- 1/2x28 is used on some threaded .380 ACP firearms
9MM
- 1/2x28
- 1/2x36
- M13.5x1 LH
- M18x1 on some older CZ models
- Other model-specific patterns exist
.357 Magnum / .38 Special
- 1/2x28
- 5/8x24 on some threaded lever-action rifles
.40 S&W
- 9/16x24
- .578x28
- M14.5x1 LH
- M16x1 LH on some firearms
10MM
- .578x28
- 9/16x24
.45 ACP
- .578x28
- M16x1 LH
- M16x1 RH on some firearms
.44 Magnum / .44 Special
- 5/8x24 on many threaded lever-action rifles
.45 Colt
- 5/8x24 on many threaded lever-action rifles
RIFLE CALIBERS
.223 Remington / 5.56 NATO
- 1/2x28
- M15x1
- M13x1 LH on some Steyr AUG models
- Other model-specific patterns exist
5.45x39mm
- M14x1 LH
- M24x1.5 RH on some AK-pattern rifles
- Other model-specific patterns exist
4.6x30mm
- 1/2x28
5.7x28mm
- 1/2x28
- 10x1mm on some FN firearms
.22 ARC
- 1/2x28
.300 Blackout
- 5/8x24
7.62x39mm
- 5/8x24
- M14x1 LH
- M24x1.5 RH
6mm ARC
- 5/8x24
6.5 Grendel
- 5/8x24
6.5 Creedmoor
- 5/8x24
- 3/4x24 on some precision rifles
6.5 PRC
- 5/8x24 on many threaded bolt-action rifles
7mm-08 Remington
- 5/8x24 on many threaded bolt-action rifles
7mm PRC
- 5/8x24 on many threaded bolt-action rifles
.243 Winchester
- 5/8x24 is common on threaded bolt-action rifles
.308 Winchester / 7.62 NATO
- 5/8x24
- M14x1 LH
- M15x1
- M18x1
- M24x1.5 RH
- Other model-specific patterns exist
.30-30 Winchester
- 5/8x24 on many modern threaded lever-action rifles
.300 Winchester Magnum
- 5/8x24 is common
- Other manufacturer-specific thread patterns exist
.300 PRC
- 5/8x24 is common on threaded bolt-action rifles
8.6 BLK
- 5/8x24 on some barrels
- M18x1.5 RH on some Faxon barrels
- Verify the exact barrel before selecting a mounting system
.338 caliber / .338 Lapua Magnum
- 5/8x24
- M18x1.5 RH
- 3/4x24
- Other manufacturer-specific patterns exist
.338 ARC
- 5/8x24
- Other manufacturer-specific patterns exist
.375 Raptor
- 5/8x24
.350 Legend
- 5/8x24
- 11/16x24
- Other factory and model-specific variations exist
.360 Buckhammer
- 5/8x24
.400 Legend
- 11/16x24
.450 Bushmaster
- 11/16x24
- 5/8x32
- 5/8x24 on some firearms
- Other variations exist
.458 SOCOM
- 5/8x24 is commonly used
- Other variations exist
.45-70 Government
- 5/8x24 on many modern threaded lever-action rifles
.50 BMG
- 1x14
- 7/8x14
- 3/4x20
- 3/4x24
- Manufacturer and model specific
METRIC THREAD PATTERNS
Metric barrel threads are especially common on firearms from European manufacturers. Some commonly encountered examples include:
M13.5x1 LH
- Many European 9mm pistols
M14x1 LH
- Common on many AK-pattern rifles
M14.5x1 LH
- Some .40 S&W firearms
M16x1 LH
- Some .45 ACP firearms
M16x1 RH
- Used on some .45 ACP firearms
M18x1 RH
- Used on some rifles, including certain older European models
M18x1.5 RH
- Used on some .338 caliber and 8.6 BLK barrels
M22x0.75 RH
- Used on some Saiga 12 shotguns
THREAD DIRECTION: RH VS. LH
Thread direction matters when selecting a muzzle device or suppressor mount.
RH (Right Hand): Threads tighten clockwise.
LH (Left Hand): Threads tighten counterclockwise.
Right-hand threads are common on American-made firearms, while left-hand threads are frequently encountered on European firearms and some AK-pattern rifles.
Never assume the thread direction based solely on caliber or firearm manufacturer. Always verify the exact barrel specification.
COMMON THREAD SIZES AT A GLANCE
Some of the thread sizes you will encounter most often include:
1/2x28
Common on .22 caliber firearms, .223/5.56, 5.7x28mm, 9mm and many other smaller-caliber firearms.
1/2x36
Found on some 9mm rifles.
5/8x24
One of the most common rifle thread patterns. Frequently found on .300 Blackout, .308 Winchester, 7.62x39mm, 6.5 Creedmoor, 6mm ARC, 6.5 Grendel, .243 Winchester and many other larger-caliber rifles.
9/16x24
Commonly encountered on .40 S&W and some 10mm firearms.
.578x28
Common on .45 ACP and also used on some .40 S&W and 10mm firearms.
11/16x24
Used on a number of larger-caliber rifles, including some .350 Legend, .400 Legend and .450 Bushmaster firearms.
M13.5x1 LH
Common on many European 9mm pistols.
M14x1 LH
Common on many AK-pattern rifles.
M18x1.5 RH
Found on certain larger-caliber rifles and some 8.6 BLK barrels.
IMPORTANT
Thread specifications can vary between firearms chambered in the same caliber. The same caliber may use several different thread pitches depending on the manufacturer, firearm model, barrel length, production year and intended use.
Do not select a suppressor mount, muzzle device or adapter based on caliber alone. Verify the exact thread diameter, pitch and direction of your firearm before ordering.
This reference is not comprehensive and may not reflect every model, generation, production year or manufacturer change. If you find an error or have an addition, please let us know.
Page last updated 10/02/2026
