hey guys

I know its hard sometimes to try to explain a malfunction through typing, but im hoping I get the scenario across pretty accurately to see if anyone has any suggestions before I rack up gunsmith fees. I am having a severe issue with my Mossberg 590 failing to eject a spent shell, that as of now, makes the weapon unreliable. I am the second owner of this shotgun and when I obtained it, it looked like it was fired maybe a few times and did not even have rub marks on any of the metal internals yet. My first range trip with it was with S&B buckshot and literally after every shot (25rds), the action would lock up to where you would have to tug the hell out of the forend to get it to eject the spent shell and cycle the next round. My second range trip I tried Federal buckshot with flite control wad, thinking maybe it was just the S&B ammo causing the issues the first time around. It was only 15rds but every single one of them cycled / ejected properly with no issues. Fast forward to today, which was my third range visit since I took ownership of this shotgun. Using the same Federal buckshot that worked great last time, the action would again lock up on every other shot or so and not eject the spent shell without either: A)  pushing forward on my foregrip then tugging back as hard as I can back and forth a few times.....or......B) putting the safety on, pressing the button next to the trigger guard that allows you to empty live rounds , pump the forend back (spent shell would eject smooth with no hangup in the action),  slide the forend  forward, take the safety off, pull the trigger to dry fire, pump back to load the next round, fire. eventually I ran out of ammo so I purchased a 10rd box of Hornady Critical defense buckshot from the range and all 10rds fired and ejected perfectly fine. Im very confused where to begin

my norinco 870 knockoff didnt like the S&B 00 buck either. I'd have to smack the stock on the ground sometimes to get it to unlock and remove the hull.

I've never had a problem with other brands/loadings.  Stop using that ammo.

The S&B buckshot that I have has a significantly greater OAL than my other shells. It will not fit in the Saiga drums.  This might be the issue?

I thought it might have been the S&B buckshot but then I tried Federal powerball slugs and flite control buckshot which worked perfect last visit, but failed today

I am not sure. Tossing another suggestion out that may have nothing to do with it - have you stripped the weapon and reassembled it? When I was 16 I put my 500 together improperly (the rails that are held in place by the trigger group) and had all kinds off issues until I figured out what I did.

I have....the very first day I got it before I ever shot it myself I watched a youtube video and broke it down entirely. Deff a possibility

I was having a similar problem with having shells occasionally sticking in the chamber of my 870 after firing. I'd have to give it an extra hard shuck (occasionally slamming it stock-first into the ground to get enough friction to push it out). I polished my chamber really well and I haven't had a problem again. I think all the crap that built up on the chamber was too thick for the shells and that would cause them to stick. Might be worth checking out on your mossy.

I had the same problem with a very old Ithaca. It would dry cycle the ammo perfectly, but would be had to extract upon firing. The cure was a VERY good cleaning of the chamber. Take a short section of a cleaning rod with a 12 gauge brush on it and stuff it into a power drill. Put the brush into the bore and spin it using the power drill. You want to get the chamber area right before the bore starts to constrict very clean. You can use the brush dipped in solvent first then use dry patches.

This will not hurt the bore and you will be amazed at the amount of residue that will come out. Since your mossy is used, you don't know how well the previous owner cleaned it.

Do you have a Side-Saddle on it, that has a screw that goes thru the receiver to retain the side-saddle, replacing the trigger group pin?  If you do, it may be too tight (pinching the receiver).

Also, remove the Trigger Group and put a drop of lube on the hammer axis pin (right on the hammer).

Let us know what you find out.

Lube it heavily & just run rds though it....had 2 590's act this way when they were new. 1 was a 590A1. After some break in the problem disappeared.

I am having the same problem with an older Mossberg 500 12ga (1974). I did the chamber polishing and even tried a different bolt with no change.
So I have a personal interest in this thread as to what could be causing the problems.

The S&B, while a good practice and training round, is unbuffered and without a shot cup. It does leave a lot of lead fouling and residue. This may have built up to a point that it is causing spent shells (which bulge slightly) to stick in the chamber.Try REALLY scrubbing the chamber and beyond. I like to use Kroil and let it sit overnight to get under the fouling.

FWIW- I just ran 20 rounds of S&B 00 Buck (the 9pellet load) through my 590A1 after shooting 50 rounds of Rem Gun Club Trap loads without any problems of any kind. This was in a gun that has not been cleaned in a while.

Update:

I wound up getting some 0000 steel wool, soaking it in flitz polish and wrapping it around a 12ga brush shoved in my power drill.....polished the chamber at half speed for 10 min slowly pushing the attachment in and out through the chamber. I also polished the action bars, the tracks in the receiver they ride on, and the inside of the receiver the bolt contacts.....I had NO idea what I was doing and knew I was taking a chance but when I was done it felt like butter inside. It did not have a mirror shine or anything, but felt super slick like a freshly waxed vehicle. Took it to the range (2) days later and ran 50rds through it of 6 different kinds of ammo. The gun ran flawless! I have not had another range trip since but that's one big step in the right direction!