The bolt face of the 257 is the same as the 7mm mag. A new barrel will be required and installation of same. Finish work would need done, either bluing or just polishing are beading if SS. The 257 is a great round. It shoots extremely flat but uses bullets of lighter weight. The recoil is not too bad but it is quite loud even with the 26 inch barrel one needs to get the most out of the enormous overbore case. While the 7mm Mag is perhaps a better elk rifle the 257 will do everything up to elk just fine and at extreme ranges.. Both rounds will leave you very sure that the rifle went off when fired but actual perceived recoil is a bit lighter for the 257. Is it worth doing???in reality, no. The 7mmMag can be laoded with lighter weight bullets and produce very similar results to the 257.. I use 7mmMags a lot and have settled on a 160 Nosler Partition with a healthy dose of IMR4350 and a CCI 250 cap. Kills like a lightening bolt and recoil is not too bad. Rmember the 7mmMag generates recoil nearly the same as a 30-06..
