Why?

Not trying to fight with you, but is there a particular reason? Its tough to get a reliable (waterfowl reliable not bird hunting reliable) semi for a cheap price tag. Sooner or later a semi is going to hang up..... I have NEVER seen or heard of one that hasn't at some point. What people consider a "jam" varies... but if the trigger is pulled and there is no boom... its a jam... if the shell doesn't eject... its a jam... you name it. With a pump, if it doesn't work... you probably short stroked it.

Just remember you get what you pay for.....