problems with a 10 round sure fire magazine for saiga .223
 

I just got a sure fire mag in for my saiga .223. When I load 10 rounds it dosen't click into place, but if I remove a round it fits perfect. I tool it apart and realized the the bottom underneath the follower are like 4/16's of an inch longer then usuall. I'm going to sand it down 1/16 of an inch at a time till it fits properly. I was wondering if anyone out there has had this problem before with there's. And I was curious on how they fixed it? Thank you for your time.