Just tried a 10 round mag I had laying around in my OOW receiver Pistol build.  It was REALLY tight at the rear.  I measured the mag well, and it seemed right.  The AMD-65 mags (20 rounders) all seemed to work well.  The Chinese mag was just .020" too wide.  Hmmm.  I could file the receiver or I can squish the magazine.  I got out the vice and took about three tries squishing it slightly more till it fit snug with no resistance going in but no rattle either.

I have a feeling that some AK magazines are just too wide.  Instead of filing your mag well, why not squeeze your mags so they fit better?  

I've done this with quite a few AR mags with good results as well.

I have one (Polish, I think) 30 round mag that is too wide, too.

Tried hand-filing it thinner, but it wasn't enough.

Not sure if I want to try your vise method. Maybe the belt-sander at work will knock off a lot more metal. :)

Scott