It would seem with extended length of the CZ 550 magazine in the 458 Lott which is probably 3/8" longer than a specified length to seat a bullet in a Lott that there is room for additional powder capacity in the case by just not seating the bullet to OAL specified.
I have loaded a 500 gr. Hornady's to a AOL of 3.565. Basically to the cannalure and a crimp.
And it matches then length of the magazine follower. There is still as lot of room left forward.
I have loaded 450 NF's to an OAL of 3.74 with plenty of room in the magazine And shot them with no issue.I had some concern with the length of the throat but no issues.
Has anyone attempted to seat the 500 gr bullets out a little further to garner a bit more powder capacity and velocity (CZ 550)?

Not sure it is needed for an application but may also allow lowering pressure to gain the same velocities.

EZ