Dry firing my Remington 870 I discovered that when the action is cocked and I have reward pressure on the pump handle the gun Jams or freezes when the trigger is pulled. When I squeeze the trigger the hammer drops but the slide is "locked" until I release some rearward pressure on it then the "slide block" drops and the slide the can chamber another dummy round and is operational. I dont recall this on any of my duty 870's. (Although they have plenty of rounds through them and are well worn) At the range with a duty 870 at work I can "pump" as fast as I can and have rearward pressure on the slide and then when the trigger is pulled, "slap" the action slams to the rear almost automatically because I maintain some rearward pressure on it! Does my 870 need to be broken in? Or some "stoning?"