mossberg 500A pump action

Question
im fairly new to the whole shooting bit, but i went out and bought a used mossberg 500A pump action 12g shotgun, with a 28in long barrel. when i shoot a cheep Winchester shell probably 7 1/2 or 8 shot the expired shell likes to get stuck in the chamber and the bolt grabbers wont hook the shell to expel it! it seems to only happen with the Winchester shells but when your at a range theres no reason to fire off expensive shells. its more annoying then anything but any ideas on how to fix this issue would be awesome. thank you, westley.

Answer
Without looking at it its almost impossible to diagnios the problem.
It could be a rough spot in the chamber, it could be weak extractors,
and many other things. It could also be a problem with the shells themself. The low dollar Winchester is imported from the low bidder.
The ones I have seen have very thin metal on the heads.
Easist solution try Federal or Remington shotshells.
Both have thier "game loads" that are cheap to buy.

How often does the shell get stuff?
Is it every shot or once in a while?