RE: JAMMING!!!!
One thing that can be a problem when shooting fast is a tendency to short stroke the action.In this case the action is not fully cycled and jams usually result.I have seen this on several occaisions with different brands of guns.I have an old 1950 model 870 that I did jam many years ago on my first goose hunt for this very reason(a very excited 12 year old) but neither this gun or my much newer 870 express have ever jammed since.If this is not your problem it is possible that there is a problem with the gun.