Why you don’t shoot 300 Blackout in a 223 barrel.


...just joking, seriously.
The 300 Blackout (7.62x35) case is shortened by 10mm from the 5.56 parent case. That 30 cal. bullet starts further back and roughly equals the smaller bullet at the point of entering the freebore.


Senior Member
I use completely different color magazine for the 300.. hard to mistake..
I use P-Mags and took the bottoms off of them and painted them red for 300 BLK. I also bought some of those red rubber bands with 300 BLK stamped on them.