300 BO bugs bite me so this came home with me. And of course good things alway happen in bedroom. Unzip it, slowly unzip it! And here come a new Baby... Welcome to this world a new pistol made here in Grants Pass, Oregon by Doc Holidays Gun. It a A-team AR-15 that have the 300BO barrel I was trying out all the left over AR stuffs that I had long time ago. I found a AR15 magazine full of Hornady VMax 223. Then my thought, what would happen if I accidentally loaded 223 ammo in 300BO barrel? They both use the same casing. I am pretty sure the pistol will load 223 in 300 barrel.