Help! 870 feeding problem while on vacation

[9mmMike]

Hi team. I’m here on vacation in the Outer Banks and the of course the lovely Mrs. insisted that we bring the shotguns. Well, we were out shooting at the fabulous Outer Banks Gun Club and I have run into an odd problem. My normally reliable 870 has dropped a couple shells out of the bottom while cycling during firing. I am guessing that the lifter is not dropping all the way after the 870 is chambered and when I pump to extract/eject, the next round is moving passed the shell latches, under the lifter and dropping out the bottom.
Does this sound right? Could it be user error? Short stroke? I can not recreate it under slow cycling or without firing.
I am shooting with a full magazine which is unusual with this gun. It has a +3 extension. It seems to happen when the mag is near full but I can not be certain of that.
I have limited internet access here and will not be able to check back in until the morning.
I will be shooting again tomorrow. I know, poor me!
Thanks for any ideas.
Mike

 

[Preacherman]

Mike, try removing the extension mag and using just standard mag and springs. If the problem is repeated in standard configuration, I'd suggest looking closely at the shell stops. If the problem only occurs with the extended mag, then I'd suggest checking the spring - it looks like it's exerting too much pressure when loaded up, so that the rounds are being kicked out faster than the shell stops can hold them up.

 

[HSMITH]

Also clean out the fire control group with some brake cleaner or gunscrubber to make sure that the elevator is not sluggishly dropping down. 3 DROPS of oil is all that the entire fire control group needs for lubrication and preservation. Any more than that and problems can be seen.

 

[9mmMike]

Thanks guys. I pulled the trigger group a couple times to inspect. It was actually wetter than I like but I did not clean or oil it. It looks like it may have been the lifter hanging on the left side shell latch. The lifter from this group is a wee bit longer than my other flex-tab lifters. I do not know why. I tweeked it a little with a craftsman pry-bar (big screw-driver) and the problem went away.
The mag sping in this gun is short and not nearly as difficult to top-off as the 870's that I have with the Wilson aftermarket springs.
Thanks again,
Mike