I had a CR-527 spawn on a brand new server (only me playing) and the magazine became stuck, unable to remove. The gun initially spawned with a hunting scope, magazine, 1 bullet in chamber, 1 bullet in magazine. I took gun to hands and then did the double tap R twice to unload the 2 bullets into my inventory, after I did that the magazine could not be removed! I tried to re-log and did not fix the issue.
I've found this gun before with a magazine and it worked ok, so maybe it has to do with me unloading the bullets immediately, not sure.
I put the errors that are reported on the server also below.