ACTUAL CONFIRMATION if CZ-527 7.62x39 Mags work for 300-221 rounds?

[este]

I've read over and over varying reports that while the 527's 223 mags need the sides cut to allow for the 300 bullet to sit properly, that the 7.62x39 version's magazine will work for the 300-221 bullets without cutting.

Personally, I think it's bullshit because the x39 case is shaped radically different from the 223 case. I would think the feed lips would be different at the minimum.

I also read that the 527 can be made to take 6 rounds vs 5 by shaving down the follower. Can anyone also confirm this?

I'd like to set the record straight so first hand only, Thanks