We converted (4) surplus 98 Mausers to 257 Roberts Ackley in 2002 as a first project.
We had to buy a mill, a lathe, a welder, and lots of other stuff.
We used Lothar Walther barrels from Brownells.
Mine shot a 0.45" 5 shot group at 100 meters with 75 gr Vmax bullets.
Since then we got more lathes, mills, welders, and have rebarreled ~ 60 rifles with the 3 shops.
That M98 257RAI project was a turning point in our lives.