I posted the question - can a gunsmith convert a new model 70 from .300 win mag to .458 win mag or .458 Lott? Is it "doable"?
Thanks,

Easily done, but not a job for a newbie.

dogcat,

Yes, the conversion is doable. Issues to be aware of:

1. Action length: The New Winchester M70 is a factory .375 H&H length action. The bolt face of the .458 (Win & Lott) is the same as the .300 Win Mag so no problems here. A .458 Win Mag can be shot from a .458 Lott chambered rifle but not vice-versa because of catridge length.

2. Secondary lug and stock reinforcement: If you are using an existing wood stock a secondary lug and crossbolt reinforcement will be required to keep the wood from splitting under the heavy recoil of the .458 (Winchester or Lott). A quality composite stock will not require the secondary barrel lug but be sure the manufacturer knows the stock will go on the .458.

yes,
easy job..

winmag, everything but the spacer below

take out the spacer, put a lug on the newly rebarreled friend, inlet and bed

2xbolts and a wrist rin

oh, and change the recoil pad