I thought this up last night as I was trying to sleep.
Here is the main idea, (most of this is written on sketch)
ok, the idea is for curved pieces of metal be attached to the pump, which curve around the barrel, just enough away from it to allow quick sliding.
This curved piece of metal will be attached to the advancer, which will advance the shells, this advancer will be as shown and will encompass much of the width of the Magazine.
As the pump is pulled back the shell is pushed back by the advancer, as shown, and as the back of it comes to the 'ramp' and begins to droop down contiued(sp) force pushes it up the ramp, as the pump is pushed back foreward a small ramp at the end of the magazine allows the shell to fall down into the barrel.
I haven't though up a ejection system yet, but with our united brain power, WE CAN RULE THE WORLD!
*looks around quickly* I uh... mean uh find a solution?