RE: Problem w/ my new pump jamming.....
I'll agree that if it's brand new, it should be a warranty repair.
I've taken apart several pumps in the past (Rem 870's, Mossberg 500's, and an old JC Higgins) to check out the operation and see how how the parts mesh to do their jobs.If the shell in the chamber is part of the jam then it 's an extraction problem, but ifthe chambered shell is getting clear andthe 2nd and 3rd shells clog up,thenit sounds like there is something wrong with one of the feed control arms or their timing.
There is(in the guns I'm familiar with)one arm that holds the shells in the mag tube when the gun is in battery, and another one, slightly forward of the first, that takesover when the pump is cycled. When the action is opened, the first arm swings clear of the case rim allowing the shell to pop onto the lifter, while the second arm swings into position to keep thenext shell in the mag tube.
If you're getting a double feed with the 2nd and 3rd shells, either the second arm isn't grabbing the 3rd shell in time, or the second arm is releasing the 3rd shell before the first grabs it when you return the gun to a battery condition.
Regardless of the problem, they'd better fix it for free.
Good luck.