Knights Armament (KAC)
HK 9mm sub-gun style adapter and will fit any 3-lug mount
The muzzle device is a standard 9mm, with different thread patterns offered. The thread patterns mostly correspond to a certain caliber, but each of those calibers is smaller than 9mm, so as long as your round is under 9mm, look for the thread pattern that matches your barrel thread pattern.
Made of 17-4ph Stainless Steel and QPQ Melonite finished.
The Griffin 9mm 3-Lug Barrel adapter is offered in four (4) different thread patterns, which you can find from the drop-down box:
The 5/8x24 and 13.5x1mm LH versions have a cylindrical machined extension added to the mount. The 13.5mm version has flats for a wrench on that cylinder extension and has the O-ring interface typical of 13.5x1 LH mounts. The other 3 Lugs are the smaller version pictured.
The 5/8x24 is meant to provide a 3 Lug mount to 30 caliber barrels but is also compatible to 9mm barrels where that thread is uncommonly used. Most 30 caliber barrels are threaded 5/8x24 thread pitch.
1/2x28 Thread Total Length: 1.4375". Based off of industry standard .625" barrel threads, added length should be ~.8125".
5/8x24 Thread Total Length: 2.125". Based off of industry standard .625" barrel threads, added length should be ~1.5".