Shop › ADV TECH AR15 ST MZL BRK JAM NUT ADV TECH AR15 ST MZL BRK JAM NUT $8.99 ATI Outdoors AR-15 223/5.56 Muzzle Brake Jam Nut, 1/2-28 Thread, Black Oxide Finish A.5.10.2255 Quantity: Add To Cart Added! ATI Outdoors AR-15 223/5.56 Muzzle Brake Jam Nut, 1/2-28 Thread, Black Oxide Finish A.5.10.2255