Someone said that you couldn't get rimlock in a Mosin with a properly working magazine interrupter. I've been playing around with my 91/30 and feeding from a stripper clip, YES you can get rimlock. Mine does it quite often and I've put in a brand new interrupter and ejector. Also the M44 will do it occasionally. If I make sure the rim of the top cartridge in the stripper is ahead of the one below it, there is never a problem, but if I get careless, it will rimlock everytime. It could be a worn magazine assembly, and I don't have a new one of those to test with.
I haven't tested the Finn "jam free" magazine on my M39 yet, but will see if I can rimlock that one too.