590 Problem - Not Loading Shells Without Massive Force

[Sanch]

I ran into a weird problem with of my 590s. To be honest I haven't shot this 590 too much accept to zero the ghost rings and maybe very little after that.

I noticed that when I pump the slide kind of loosy goosy, it doesn't pick a round up from the tube. So I analyzed what's going on with the operation and looked up technical terms to best describe it.

It seems like in normal operation, when you pump the slide, the elevator moves down inside the receiver as the bolt goes back. The elevator exerts force on the cartridge stop, which pushes the cartridge stop in and frees a shell from the tube. The shells don't "want" to be in the tube because the follower has a spring behind it but the cartridge stop holds the last shell in. When you push that cartridge stop in with your finger you can unload rounds from the tube (as I already knew from operating 590s for years), and now I figured out the elevator is what's pushing that in to release rounds.

Well, under casual pump force, the elevator isn't dropping down enough to engage the cartridge stop. If I do a super forceful racking, it works fine. I'm not sure if I got spoiled that my main 590 is NP3 coated and pumps like butter, almost no friction. So maybe I forgot that you really do need to massively force the pump. But I wonder if something is off inside my gun.

Maybe it needs to be worn in and if I forcefully rack the pump a few thousand times in my living room over a few hours it will break in? Or maybe I jacked something up inside the receiver and the elevator isn't being pushed down enough because something is off in how I reassembled it. I don't remember taking this gun apart ever, but I might have. I have taken my other 590 apart many many times to clean, to install (and uninstall and reinstall and re-uninstall) the mesa tactical side saddle.

I'm somewhat familiar with taking them apart, so if this sounds like normal break in required, please let me know. Or maybe I need to dissassemble and reassemble and if so is there any error that might specifically cause this? When I say forcefully rack the slide I mean pretty forcefully required to load a round from the tube. To the level of force where I'm afraid I'll get off target a bit too much and also that there's a much much higher chance of short-stroking because even if I full-stroke, if I don't put enough pressure, it won't strip.

I'm pretty dang sure on any 590 I played with up to now, I could gently ease the slide back and the elevator would drop enough to release the cartrdige stop just fine.

[peterb]

I’d take it apart and look for burrs or other obvious problems. My experience with a few Mossbergs is that the stamped parts can be fairly rough around the edges, and a little cleanup can go a long way.

You might also compare the elevator and shell stops to the ones in one of your “good” Mossbergs and see if you can see any differences.

[Tensaw]

Yeah, that ain’t right. I agree with checking for burs and whatnot. That said, I bought a 500 a few years back that was fine out of the box. Several boxes of shell later, it started failing to unlock the action after a shot. Not so handy on a duck gun and you miss as much as I do. Seems like I tracked down the problem to a specific part. When I called mossberg to try to get the part, they wanted me to send the gun in. Which I did. And they fixed it. I had to pay to ship it there which sorta sucked. And com where nonexistent while they had the gun. If I remember correctly, they fixed it and had it back to me in a couple of weeks. No problems since.

[fixer]

I'll add to the choir here...check for some burrs or something binding up or even out of spec.

[willie]

I ran into a weird problem with of my 590s. To be honest I haven't shot this 590 too much accept to zero the ghost rings and maybe very little after that.

I noticed that when I pump the slide kind of loosy goosy, it doesn't pick a round up from the tube. So I analyzed what's going on with the operation and looked up technical terms to best describe it.

It seems like in normal operation, when you pump the slide, the elevator moves down inside the receiver as the bolt goes back. The elevator exerts force on the cartridge stop, which pushes the cartridge stop in and frees a shell from the tube. The shells don't "want" to be in the tube because the follower has a spring behind it but the cartridge stop holds the last shell in. When you push that cartridge stop in with your finger you can unload rounds from the tube (as I already knew from operating 590s for years), and now I figured out the elevator is what's pushing that in to release rounds.

Well, under casual pump force, the elevator isn't dropping down enough to engage the cartridge stop. If I do a super forceful racking, it works fine. I'm not sure if I got spoiled that my main 590 is NP3 coated and pumps like butter, almost no friction. So maybe I forgot that you really do need to massively force the pump. But I wonder if something is off inside my gun.

Maybe it needs to be worn in and if I forcefully rack the pump a few thousand times in my living room over a few hours it will break in? Or maybe I jacked something up inside the receiver and the elevator isn't being pushed down enough because something is off in how I reassembled it. I don't remember taking this gun apart ever, but I might have. I have taken my other 590 apart many many times to clean, to install (and uninstall and reinstall and re-uninstall) the mesa tactical side saddle.

I'm somewhat familiar with taking them apart, so if this sounds like normal break in required, please let me know. Or maybe I need to dissassemble and reassemble and if so is there any error that might specifically cause this? When I say forcefully rack the slide I mean pretty forcefully required to load a round from the tube. To the level of force where I'm afraid I'll get off target a bit too much and also that there's a much much higher chance of short-stroking because even if I full-stroke, if I don't put enough pressure, it won't strip.

I'm pretty dang sure on any 590 I played with up to now, I could gently ease the slide back and the elevator would drop enough to release the cartrdige stop just fine.

Dan lehr who posts here repaired these during his many years as an l.e. armorer. He knows more about Mossbergs than Mossberg knows. Ask him.

[DDTSGM]

Willie may have been exaggerating.

Mossberg magazine springs are kind of notorious for going away quickly, especially if left loaded. I know that supposedly it is the cycles that kills springs, but that doesn't seem to be the case with Mossies.

So, make sure the mag tube and the follower are clean. And check the spring. Sometimes the follower might get gummy and rub against the mag tube, in that case it could case the condition you describe, the 590 should have a metal follower, though, so again, make sure everything is clean in the mag tub, no lube.

In your OP you described the action of the cartridge stop, which is located on the right side of the receiver when you have the shotgun oriented loading port up. Since you use this to unload the shotgun, you are familiar with it's function. The cartridge stop is it's own spring, it moves in and out as the tab on top of the cartridge stop interacts with a bevel cut on the action bar. You need to make sure the channel this part rides in is clean and free of grease/dirt, etc. Also make sure the tab on top is intact and the bevel on the left action bar looks okay.

On the other side of the receiver is the cartridge/shell interceptor latch. it is the one that fits in the hole in the receiver. When the cartridge stop is moved out of the way, the interceptor latch is rotated up to catch the next round in the mag tube. The back of the bolt slide hits the tab on the back of the interceptor latch driving it up to catch the next round in the mag tube. As the action bar slide moves forward the stop latch comes off the bevel on the left action bar and moves into the receiver area to stop the next shell, literally several inches later, the right action bar contacts the fron lug of the interceptor latch, driving it down and allowing the next shell to come to rest against the stop latch.

You really don't see the interceptor latch when you look into the loading port, especially if the tube is loaded. The Mossberg stop and interceptor system is pretty robust, make sure the receiver is clean, make sure the parts are intact:

tab on stop latch and bevel on corresponding action bar

front and rear tabs on interceptor latch and tab on correponding action bar that contacts front tab of interceptor latch.

Should work.