Why Do Thread Pitches Matter?

Thread pitch matters because the wrong threading can be dangerous. Attaching a muzzle device with an incompatible thread pitch can result in catastrophic failure, damaging your firearm – or worse.

Before buying any threaded accessories, check your barrel’s thread pitch to ensure a secure fit.

Standard US Thread Pitches

For rifles, the most common US thread sizes are:

• 1/2×28 – Standard for most .22 caliber barrels
• 9/16×24 – Found many .30 caliber rifles and medium contour barrels
• 5/8×24 – Larger option for .30 cal and bigger bores and heavy contour barrels

Let’s dive in.

1/2×28 – .22 Long Rifle and .223 / 5.56 Caliber Standard

The 1/2×28 thread pitch is the standard for .22 caliber firearms. You’ll often find it on:

• AR-15 in .223/5.56
• Ruger 10/22 and variants (Charger, Takedown, etc.)
• Marlin 22 LR
• Smith and Wesson M&P 15-22

This thread size works because a .22 caliber bore has enough material in the barrel wall to support a 1/2-inch OD thread.

However it’s not ideal for .30 caliber barrels. Some rifles have a 1/2×32 thread pitch for .30 cal barrels to prevent mismatched threads – such as threading a .30 cal barrel into a .22 cal suppressor. Always check before installing a muzzle device.

9/16×24

The 9/16×24 thread pitch is often found .30 caliber style rifles, such as:

• .308 Winchester
• .300 Win Mag
• .30-06 Springfield
• .300 WSM This thread size has thicker barrel wall than 1/2×28 so it’s a good choice for high powered rifles. You’ll find it on platforms like AR-10, FAL and M1A/M14.

5/8×24 – Bigger Threads for Bigger Bores

The 5/8×24 thread pitch is similar to 9/16×24 but for larger barrel diameters. This is used on:

• .30 caliber and larger heavy barrel rifles
• .308 AR bull barrels

If your barrel has enough OD, opting for 5/8×24 can give you stronger and more durable threading.

Metric Thread Pitches

While US threads dominate in the United States, metric threads are not uncommon – especially on foreign made firearms.

14×1 LH – The AK Thread

The 14×1 Left Hand (LH) thread is standard on AK variants. Interestingly this thread pitch is dimensionally similar to 9/16×24 LH thread pitch, which makes sense since both are used on .30 caliber rifles.

Left Hand vs. Right Hand Threads

Most threads are right-hand (RH) threads, meaning they tighten clockwise. But some barrels use left-hand (LH) threads which tighten counterclockwise.

Why Left Hand Threads?

Some firearm manufacturers and countries use LH threads for various reasons:

• To prevent muzzle devices from loosening due to recoil forces
• Standardization in some military designs (e.g., AKs and FALs)

For example some FAL barrels come threaded 9/16×24 LH. Unless specified as LH, threads are assumed to be right-hand (RH).

Professional Advice

Choosing the right barrel threading is important. Any good suppressor dealer or gunsmith can help you choose the right thread pitch for your caliber and muzzle device.

Don’t take advice from just anyone – leave Bob at the tackle shop to the fishing tips!

Conclusion:

This covers the most popular thread pitches but there are many more out there. Did you know an UZI barrel nut uses a 1×18” thread? Some suppressors, like one from Vector Arms, can even replace the UZI barrel nut itself – nice!

If you have any threading or muzzle device questions contact a professional before making any changes.

⚠️ Warning

This article is for educational purposes only. Before modifying your firearm, consult a gunsmith. Always prioritize safety and compatibility when working with threaded barrels.