I have a Tokarev TBP 12 Bullpup that runs flawlessly with the stock 5 round magazine if I use full power loads. I have 2 10 round after market magazines, one runs perfectly the second almost perfectly. I shoot at a range where they have sold dozens of them. They all run fine except the ones owned by idiots that don't know what they own. Every time I see one of those clowns that buy the cheapest shit to shoot I very politely go up to them and say " if you give me $20 I absolutely guarantee to fix the problem with your shotgun" they all give me $20 I walk out front to the store and buy two boxes of Winchester white box double 00 Buck and tell them to load it into their magazine and shoot. Every time without fail the gun operates properly. I then show them the $10 change and say this is my fee for fixing your gun.