I just bought my SLP MK1 used. Very lightly used. I can only get seven 2.75" shells into the magazine. I've tried Winchester Military Buck and S&B Buck. I can nearly squeeze eight in with the win Buck. But the eighth on the S&B sticks out from the magazine by atlease half an inch. I have no idea what's up. Anyone have tips or insight. I took the shotgun mag spring out. No obstructions that are obvious.