Which muzzle brake / compensator fits my weapon?
First check whether the barrel of your weapon has muzzle threads, and what type of thread this is.
This thread is either a UNEF thread (UNEF = Unified Thread Standard) or a metric ISO thread.
You can often find the type muzzle thread of your weapon in the manual or on the manufacturer's website.
• UNEF thread:
UNEF threads used for muzzle brakes / compensators are in 90% of the cases 1/2”X28 TPI or 5/8”X24 TPI threads.
The number before the X stands for the outside diameter (indicated in inches), the number after the X stands for the number
of threads per inch or threads per Inch (TPI)
1/2 inch threads have an OD of 12.7mm and 5/8 inch has an OD of 15.87mm.
Type ½”X28 thread (12.7 mm OD, 28 threads per inch) is commonly installed on weapons from American manufacturers and on
some European weapons (AR-15, M16, etc.), including small-bore weapons up to 6 mm in diameter.
diameter, e.g. 22, .223Rem, .222Rem, .224
Note that manufacturers such as Oberland Arms often use ISO threads on their AR15 clones. Some US weapons have a
thread of ½”x20 TPI
Type 5/8”X24 thread (15.87 mm outer diameter, 24 threads per inch) is usually on AR-10 and usually for all calibers up to 8 mm Ø,
applicable for example for: .308win, .300 win mag, 7.62 × 54mm R, 06/30 and others.
• ISO Thread:
Metric threads (ISO threads) are often used by European weapon manufacturers.
This can easily be recognized by the always preceding M, such as M14X1, M15x1, M18X1, etc.
The M stands for metric, the number after the M, for example M15X1,
stands for the outer diameter of the screw thread in mm. M15X1 thread has an outer diameter of 15 mm.
The number after the X stands for thread pitch (the distance between the threads in mm), in this case 1 mm.
Note that many former Eastern Bloc weapons have the M14x1 left-handed muzzle thread (counterclockwise).
This is often referred to as M14x1LH
So you can easily check with a vernier caliper or ruler whether your weapon has an ISO or UNEF thread and which pitch this thread has.
Muzzle thread Outer diameter
1/2"x28 12,7 mm
5/8x24 15,87mm
M14x1 14mm
M15x1 15mm
M18x1 18mm
• Clamp or twist-on muzzle brake
If your weapon doesn't have a thread on the barrel, you may be able to use a clamp or twist-on muzzle brake.
Note that twist-on muzzle brakes are often only suitable for a certain type of weapon.
For the clamp muzzle brake you need to measure the diameter of the barrel very carefully.
If there is no suitable clamp or twist-on muzzle brake for your weapon, you can ask a gunsmith to make threads on your barrel
• Caliber:
The caliber stated with a muzzle brake / compensator is the maximum allowed caliber.
With a muzzle brake in caliber .308 you can use all calibers up to .308.
So you can put a .308 muzzle brake on a .233 rifle but not the other way around.