ATI MOSSBERG AR15 16" M4 5.56 BARREL 1/7 TWIST
These are all melonite coated inside and out. Melonite is stronger and more effective than chrome lining because it does not pit.

All are chambered and marked for 5.56 with a 1x7 twist. They include the M4 barrel extension with M4 feed ramps. Made by Mossberg