Browning BPS releases two shells at same time

[papabear]

I just bought this used BPS Stalker for my son-in-law and it has a problem.  Load up the magazine, then cycle pump action to chamber a shell, and it often releases two shells, creating a jam.  Usually does this when barrel pointed slightly skyward, but sometimes in other normal shooting positions.  Sometimes it continues to do this after each shot, sometimes not.  

There is a small "retainer" (not proper term) on L and R side which curve inward to hold shells in magazine.  The LH one (with the small "button" on it) seems to cycle in and out OK and appears to do its job, but the one on the RH side seems to stay flat against the receiver and its outward curved portion does not engage rear of shell in magazine.

When I clear the jam by pushing the 2nd shell back in the receiver, it is hard to get it to stay there.  

I have always had the cantilever mount slug barrel on , and have tried several different brands of slugs, they vary some but all cause problems.  I have not tried it with the bird barrel on.  

I was going to dismantle and clean it for starters.  What do you suggest?
Thanks.

[dukkillr]

one of the things i love about the bps (and there are many) is that you can tear the whole thing appart and have it back together in 20 minutes... i know exactly what peices you are talking about, and it wouldn't surprise me if one of them isn't seated right on the pin... in my bps's i've never experienced any sort of bending or wear on those pieces so i can't imagine that the part itself is defective (although obviously that's possible).  If you knock the pins on the reciever out you can remove all the guts although if you just go after the pin closer to the trigger guard you should be able to check the alignment of those catches without having to take the bolt and ejector out.  Be forewarned, getting the trigger mechanism back in with those catches in place is a tedious job.  My experience has been that if you just keep trying eventually the stars align and it just slides into place.  That being said, when i said it takes 20 minutes to put a BPS back together, 19.5 of those minutes are trying to get the trigger mechanism to seat all the way down with those ejectors refusing to cooperate.

[papabear]

When you say the catches may not be seated right on the pin, is this something obvious is I look closely, or exactly how can they NOT be seated correctly?  An error by the last guy who took it apart?

I do have some mechanical ability, but I am sure no gunsmith.

[dukkillr]

here's what i'd guess from what you said.  I bet the guy before you got pissed off when he couldn't get the trigger mechanism reseated with the catches in the right place on the pins (it's getting the catches out of the way that makes reseating the trigger mechanism so frustrating) so he put one of them back incorrectly.  It's easy to tell where those catches are supposed to fit on the frame when they're in the right spot.  You won't do anything catestrophic by taking the trigger out and looking, just knock the downward most (closest to the trigger) pin out and the trigger assembly can be pulled out.  Once you do that it'll be obvious if something's wrong with the catches themselves or the way someone else put them back in.

[papabear]

OK, I will give it a try and will let you know what I found out.  It may be a few days before I get the "uninterrupted" time I need to do it, but I will.  Thanks again.