MDS has been a huge help thus far so I am posing another question for help. I am building a 300 blackout rifle. The lower is complete and I am moving onto the upper. In my search for barrels I was curious if 300 AAC blackout barrels must be stamped/advertised as HBAR or if barrels of this caliber are by default HBAR as most measure 0.750 at the gas block. I should mention that I am planning on a 16" barrel length.
Thanks for your help.
Thanks for your help.
