Blind pinned and welded muzzle devices are often encountered on barrels to make the non-NFA minimum 16″ length on rifles. In the shop, we’ll often encounter them on AR-15/M16 M4 barrels that have a muzzle device making length. As a shooter’s needs change, they’ll often want to swap hand guards or rail systems and the muzzle device needs to come off so the gas block and barrel nut can be removed. After two decades of using every method I could think of, this simple technique of plunge cutting with an end mill seems to work the best for most applications.
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Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.
Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.
Another word of caution before cutting off a muzzle device: Don’t cut too deeply. You’ll ruin the barrel if you do. One most 223/5.56 AR type rifles, the muzzle threads are 1/2″-28. This means you have to do a little math before you start cutting out the pin to ensure you don’t start getting involved with the barrel.
I start by securing the muzzle device in the milling machine’s vise. Since most of the muzzle devices I remove are expensive, I try to remove them in a way which allows them to be reused. In this case, I wrapped the muzzle brake in some blue painter’s tape to protect the finish. Using a 3mm 4-flute, solid carbide, center-cutting end mill, I begin to make a slow plunge cut into the weld.
I’m careful that I don’t cut too deeply. Often, as in the case here, the pin will be ripped out by the end mill, allowing the muzzle device to be unscrewed and reused since damage to the part was minimal.