I bought two of the black 7.62 40 rd. plastic mags that I found for $29 N change.
At the range I had to take out the pocket knife to clear a few spots that were hanging in order it get the mag in the gun far enough to cycle.
They were tight real tight, but after a little whittling & cycling a few rounds through mag and gun they work good now.
I don't like plastic mags but the price was right & I wanted a few more than the normal 30 rounders.
If everyone is thinking alike, then somebody isn't thinking.
George S. Patton