I have a rifle that is presently chambered in the 458 win mag,can it be reamed out to the lott but in two separate steps ? I am trying to get the best throat for the bullets that I would want to shoot out of this rifle and they would be shorter than the standard 500 grainers,so can the chamber be reamed out to the Lott length without cutting a new throat at the same time ? thanks for your help,I am kind of new at this.

Last I heard, the 458 Lott is a SAAMI chambering. You change ANYTHING and it is no longer a 458 Lott..it's a wildcat and must not be stamped "458 Lott".

Future owners could develop a real problem with your special throats..can raise pressures way beyond acceptable limits.

cut a lott chamber with a conversion reamer -- don't shorten the throat, that's a bad idea ..

Gentlemen,
thanks for your advice,I am going to shelf that idea.

458 Win Mags have extremely long throats compared to the SAAMI Lott, so even if you ream with a normal Lott reamer you might not be cutting the throat (CIP Lott is long and tapered like the WM).
I checked OAL to lands on my CZ550 WM and even with the long magazine, it would not be possible to load most bullets any where close to touching the lands irregardless of brass length. The 350 Hornady and 400 Speer bullets are completely clear of the WM case .300+ inches before the bullet contacts the lands. Accuracy with light bullets isn't great, but the 450TSX and some 500gn jacketed bullets shoot near 1moa. Have heard though, a normal conversion to the Lott will help with the lighter bullets.
Here is the thread discussing the throats-
http://forums.accuratereloadin...201027511#9201027511

86thecat,
thanks for posting,gives me an idea of what's going on !