by Hoot » Sun Nov 17, 2019 8:22 pm
The 5.56/223 bolt face fits the .378 OD rim of that cartridge, The 450b rim which was originally spec'd at .473 OD, would not fit into the bolt of a 5.56/223. So, the 450b bolt is "hogged out" to an internal diameter that fits the .473 rim. The outside of either caliber's bolt is the same. Either one will fit into the AR 15 barrel extension. In the normal operation, there will be some shining of the points that rub against one another. That is to be expected as they get "broke in".
Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.