I tried and tried with Gevarms. Owned tons of them. The limiting factor is the factory 8 round magazines. The rifles typically only come with one. Finding additional magazines runs into several problems...either none are available at all, or the ones you can find don't work, or the new repros don't work at all.
The only mags I ever had that worked at all were the factory 8 rounders that came with the rifle new. (probably hand fitted)
Any 15 or 20 round mags I had didn't work at all.
I'm talking the steel tube receiver rifles (A3 and A6) btw...the white metal E2 takedowns have weak receivers that can bend or get destroyed by using high velocity ammo.