I was shooting double-trap today with the TANK and half way through the round I got a boom-rack-click! Hmm....thought I had a dud but the chamber was empty and the second shell was still in the magazine. I was loading the first round in through the port and then adding the second round into the magazine as per usual but it would not come out of the magazine, hence the dry fire. Here's what went down:

The humble "cartridge stop" and "cartridge interrupter". They stop rounds from squirting out of the mag tube too soon before the elevator gets down all the way to catch it- the elevator then lifts it up to the bolt which then rams it into the breech/chamber, while the interrupter/stop hold back the next cartridge in the magazine. They are on opposing reciever sides and slightly offset so the shell goes past both one at a time before exiting the magazine.

I had another pump that would double feed when stuff got under the interrupter. It prevented the tang on same from catching the rim, which in turn allowed the magazine to empty out onto the elevator and then stack up and fill the chamber with rounds. Not good, watch chukar laugh and run away. Oh I was a little miffed.

But this time I was getting no feed. It was the stop that had become mis-shapen- how I don't know, possibly me doing a short stroke jam that bent it, who knows, either who, that was the cause. The bolt carrier/elevator wasn't hitting it and not knocking it out of the way to allow it to plop out onto the elevator.

The little levers are usually 2-8" long- sometimes floating in a recess, some have a verticle pin in through the bottom of the receiver side with a spring behind the lever. Both have a curl or tang that stops the shell at the rim, it's sometimes what you catch your glove on loading rounds into the mag tube, when not pinching it on the elevator. The big Mossy has a unique elevator so that won't happen, when in battery it's wide open on the bottom for super easy loading.

If junk gets caught under either or it's is not shaped correctly it either wont feed rounds or dump the magazine's contents.

So if you are having issues with double feeds ( cartridge interrupter) or no-feed (cartridge stop) from the magazine these two little levers will most likely be the cause. A blast of air to/under the "interrupter" (don't blow the spring out!) or slight tweak to the "stop" where the bolt carrier or elevator hits it is all it takes, SLIGHT tweak, talking thousandth's as I bent it too much and started dumping rounds way too soon - and only if it's a stamped part. A cast part will need replacing if it's worn out. Easy fix either way, though it did take me some time to figure out the timing and why, and, several teardown, trials and error. But I got it working again 100% no malf after 200 hard and fast as I could cycles ( I think the sound of that pump racking made my neighbor nervous, heard his door slam ).

Pic has an example of the "stop" showing the curled tang that arrests the shell at the rim before the elevator comes down to get it, the "interrupter" is opposite of it, hidden. Interesting cycle and timing of events. Works the same way on a pump as well as semi-auto.

Hope this helps someday and feel free to pass it on if you like!

what breed of shell is that???
the only problems Ive seen is with a mossberg maverick that we used back when I was rabbiting. it would slip over the rim of the shell of plastic packaged rounds of falcon, the cardboard boxed stuff had a different rim shape. have a look as some are on quite an angle almost 45 degrees. others are square. this was a real pain as you would have an empty stuck and a full trying to get in and rabbits getting away.....

I think it's a Rio target load. I have a bag fula random ammo for Annie Oaklie.

got all technicle like tonight and stripped the pump FINALLY after 5 years of hard use mud blood and crap galore. I bit the bullet and popped out the two pins dropped out trigger block and soaked it in petrol before giving it a good CRC to finish. blasted out the action with more CRC and wiped out as much crap/crud as I could see. sheesh it a wonder it was funtioning at all, only did it as it was getting a bit sticky on opening sometimes. will promise to do it more often from now on.

Great article Slim. Wish I was allowed to have a pumpie out here...but thems is vewwy vewwy nasty guns, so they is illegal.

Have a few mates that swear by cleaning the trigger group etc of their shotties with 2 stroke engine fuel Elvis. They claim that the oil residue left when the petrol dries off is more than sufficient to lube the action and it's thin enough not to attract dirt, dust and other crap and corruption.

Myself, I use graphite after cleaning with Brakleen.

Here's an interesting website for those interested in shotgun headstamps.

Shotgun Headstamp Info

fuunily enough the petrol came out of my Stihl so 2 stroke it was!!! sure is alot of headstamps out there!!!