I have a .450 Marlin built on a P14 Enfield action. Gun chambers factory ammo with no problem. I bought some used .450 Marlin brass that was not fired in my rifle. When I resize it and reload the cartridge using cast bullets it will not chamber in my rifle. Round will go into the chamber but bolt handle will not close on the round. OAL is not the problem.

Comments or suggestions? Thanks for the help.

Will the sized brass chamber? If so, check bullet diameter; if it is .458 or .459 look at the bullet ogive for rifling marks. Some cast bullets may touch the rifling on their ogive/front band even though ok on oal.

Check your brass length. If it is too long it won't chamber correctly. Usually this is more of a problem on levers, but you may have a snug chamber on your custom p14.

John

Does the brass chamber with out the bullet in it.
could be the bullet is oversize or that it needs to be seated deeper.