Looking to get the XM177 Flash Hider & Grenade Ring to make a 11.5" barrel at least 16 inches without going to much over that. Brownells info says with the flash hider and grenade ring it's 4.45" long. That puts the length of a 11.5" barrel with them at 15.95".

My question is, would a crush or peel washer put it over 16"? Or would having a muzzle thread protector machined down to .060"/.075" long work? If I went with a machined down thread protector (or something), I could probably have it machined long enough so I wouldn't need the grenade ring. It'll be pinned and welded.

Or does anyone knows of a 4.5" to 5" long muzzle device? As mentioned, I don't want to go much over 16 inches.

Thanks, NYH1.