I just got a used 1300(18"bbl,7rd mag extension),and when you fire it,it unlocks by itself and the bolt/carrier moves back about an inch,same motion as if you were chambering another shell,but it seems like the lockup lets go too easily,or maybe too soon(?).It can be held in place,but the only thing keeping the empty shell fully chambered is the forward pressure you're putting on it.I didn't try it one-handed,so I don't know how far it will move to the rear when unsupported.The lockup is fine by itself,you can try as hard as you want,but it will not unlock until you pull the trigger or push the release button.Any ideas?Hopefully it's an easy fix.Thanks in advance to anyone that knows...