870 Express Not Chambering Rounds

[EXPRESS61]

Good evening, all.

I have an 870 Express which I bought around 2007. All told, I've probably only fired about 1000 shells from it since then, mostly shotshell chasing clays. However, the gun will not consistently chamber shells. I've found that if I load 4 shells, it will not chamber a round, but if I load only two, it might. I meticulously cleaned it and it functions normally. From what I can tell (from looking at an 870 diagram), the shell latch will not release a shell. I've changed types of shells as well with no luck. Does anyone have an idea of what is going on and how to correct it?

Many thanks.

v/r

EXPRESS61

[Scorpion8]

Is it only on shells from the mag tube? Can you cycle 1 hull thru the gun consistently? Does it damage a hull when it won't cycle?