I had something similar happen once in a 300 NM Hunter mag. Took it apart and flipped the spring, worked like every other one I have after I did that. Maybe try that?
I’m doing load work up on my 300 WSM right now. I have a .220” freebore on a medium LPA Fuzion. If you are wanting to go with 215-230 bullets I think it would work quite well, but you’d definitely want a long action. I have to jump the 215s a fair bit to run from the mag. 208 ELDMs and 212 ELDXs...