Yes, it is a simple chamber reaming job. But with a catch....not all actions are suited for the conversion. The .458 Winchester was designed to fit in a " standard" length action and was made in many rifles that would NOT be large enough for the .458 Lott. Perhaps the best known, and most often used, action that will work for the rechambering is the Magnum CZ-Brno. CZ chambers it' s .458 Winchester in the same action that it chambers the .375 H&H, (and for that matter will handle the .505 Gibbs). Usually you do not even need to alter the feed rails when converting CZ' s from .458 Winchester Magnum to .458 Lott. And ironically the CZ often feeds more reliably AFTER it has been rechambered to .458 Lott. (Apparently the .458 Winchester is so short it causes feeding problems in the large action.)

Maybe the best of all....the Magnum CZ is currently one of the " best buys" on the market! And yes the .458 Winchester does fire in the .458 Lott chamber....just like a .38 Special in a .357 Magnum! A twofer!

Good luck!

P.S. Any Ruger No. 1 Tropical in .458 Winchester lends itself well to the conversion as well!