Problem with Mossberg 500

[lumpia]

So when shooting trap with one in the chamber and one in the mag, I'll fire the first shot, pump it and *click*. The 2nd shell ends up on the ground somewhere. For some reason the shell dumps out of the magazine. I'm not sure if it happens during firing or it happens during cycling.

What would cause this? Is it a short stroke deal or some other type of operator error? Is something wrong with the loading port somewhere? It happens maybe 3-4 times out of a box of 25. I usually use cheap Walmart ammo, Winchester AA or the Federal equivalent.

Thanks for any info. Hopefully watching a clay fly untouched can be a thing of the past.

[11011500a]

Turn it upside down put three or five shells, snap caps if you have them, and watch the action. The cartridge stop could not be moving in-sync with the cycling. It could be as simple as just bending it a hair back. the ammo doesn't matter. don't get in a hurry just watch it and do it a couple of times you should see what's going wrong. I have a 500 it did it to me maybe twice out of a hundred rounds. Good luck.

[acegunnr]

It is due to short stroking. If you hesitate a fraction, the round will fall out.

[The Cable Guy]

I also think it may be caused due to short stroking.
Perhaps when you rack the action back, the elevator isn't going all the way down, impeding the next round from being loaded onto the elevator into the chamber.
Instead, it is blocked by the elevator, and when the elevator is pulled up back onto the bolt, the round simply falls out of the loading port.

[Rust]

Another thing to look at could be an operator error issue. I've noticed the same thing shooting doubles with my 500. I found that sometimes i was not getting the round pushed all the way past the shell stops. I'd load and get the rim hung up on the edge of the receiver or magazine tube rather than all the way in, and the recoil would cause it to pop loose and fall out.