Curious here, and I know this is diverging slightly from the topic, but with this stoppage/jam/malfunction, are you referencing the stoppage induced by having a round stuck between the bolt and the shell lifter, with the bolt closed? I ask, because I'm not conceiving of how a double-feed requiring impact to clear would be possible with my Mossberg 590, but I have experienced that exact user-induced failure with an 870 during a stress course, and witnessed it a few more times with worn retention teeth on 870 magazines (combined with clumsy/fumbled reloading), allowing the just-loaded round to pop out of the magazine and between the lifter and bolt.Silent Professional wrote:3. While we're on the subject of butt stocks, I highly recommend that you ditch the adjustable stock and go with a fixed, shorty stock. I recently finished up teaching a shotgun instructor course to 30 instructors, all LE and military. One department had installed the useless Knoxx (now Blackhawk, I think) stock on their department's weapons. When I set up the short stoke / double feed stoppage clearance drill, the folks with the Knox pogo stick on the end of their 870's could not clear the double feed. Ditto with the adjustable stocks. If you need to hold down the action release and pull down hard on the fore end while slamming the butt stock as hard as you can on the deck, it's a no - go with the Knoxx stock and collapsible stocks.
If this is indeed the jam you're referencing, I'm in full agreement on the Knoxx/Blackhawk stock. If it's not, I'd like to know exactly what jam you're inducing, so I can figure out a way to avoid doing it with my own Mossberg (fitted with the said pogo stick, which is wonderful for recoil reduction, but admittedly has its short points).