Is it as easy as reboring the barrel to 35 cal or wound the chamber need work? Thanks, Optik1

Case dimensions are different, so yes chamber work. then feeding work. The one I had rebored I just put a detachable mag in. Ugly but it works.

I rebarreled a Sako L61R 7mm Mag to a 358 NM. Used a Sako factory profile 26" barrel from Shilen. No feeding work required. 4 rounds down. Wish I had gone a little longer on the throat - I like to seat my bullets long.

Thanks for the responses. Optik1

I have taken a Winchester model 70 Classic and a Ruger Mark ll, both of which were chambered in .338 Win mag.,and have had them rebarreled to .358 Norma magnums. I had absolutely no feeding or extraction issues with these conversions-they ran like they were specifically designed for the Norma without any action modifications. You may want to explore using a .338 Win. Mag. donor action and rebarreling in your cost analysis. It worked for me…

I have two 358 norma mags one built on a Remington 700 that started Life as a 7mm Remington mag and an Inter arms mark x that was as a 7mm Remington mag, neither one required feeding work and feed just fine from the factory magazines!