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Discussion Starter · #1 ·
Hey guys,

I have a 18" 5+1 590A1 that was a police trade in.
It looked like it was never cleaned when I got it and chunks of carbon or maybe even pellets came out of it when I went through it. It wasn't too... bad at first but it's completely unreliable right now, it jams and misfires constantly.

It looks great out side though. I thought about just getting rid of it but I think I need to get in touch with mossberg and get all new internals or something. I'd get it *tough or *dura coated too eventually.

I've had trouble finding a mag tube extension that will match up with the length of the barrel though... I've seen +1's with sling swivels but they're too short, I ordered but returned one from Choate because it was too long... Can someone help me eliminate this guess work if they know what will work, or atleast as close as possible??? I love how shotguns look when the barrel length matches the mag tube length. Help me please!
 

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I'd be more concerned that it's not reliable... what exactly is it doing? Shells releasing too early/2 at once? not chambering properly? firing pin broken? etc.

I don't know of any extensions that match the 18.5" barrel but I'm sure they exist.
 

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Discussion Starter · #3 ·
I'd be more concerned that it's not reliable... what exactly is it doing? Shells releasing too early/2 at once? not chambering properly? firing pin broken? etc.
Sometimes the shell will jam on it's way into the chamber after it's left the tube, like it will bind up racking forward after it's been racked back. Maybe it needs more lube...

Last time I took it out it Failed to fire more times then not. Trigger clicks but no boom...
 

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Well that ain't good... have you stripped the bolt? I fixed one 500 that had a similar problem on chambering, replaced the elevator etc. but what it really needed was the extractors filed/polished so the rim of the cartridge could slip up between them easier. Take out the bolt and hold it, and see how difficult it is to slide the rim of a shell up between the extractors. If there's any binding/shaving of brass/etc. you could do a polish job.

Dunno about the misfire issue... did you disassemble the bolt or anything during your once-over? I assume it's the new-type spring-loaded firing pin...
 

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Discussion Starter · #5 ·
Could be anything man. Its my first Shotty and I pulled it apart almost a year ago. I have nothing to base what I was looking at on. Doubt the gun has a new style anything on it. When I get home ill pull it apart and take some good pics of it. I wouldn't be against sending it to mossberg or getting all new internals for it. Lazy cops lol. I've only shot the thing like 3 times. I didn't pull the firing pin out of the bolt or anything, didn't see how... I doubt I put it back together wrong.
 

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Well the guts of these things are astoundingly simple and easy to understand, even for a doofus like me. Just don't take the trigger group apart.

It's possible there's just some crud/corrosion in the firing pin channel or the spring's grunged up or something. It seriously takes like 30 seconds to field strip those things. Take it apart, give everything a good hose down with solvent, brush it out, oil it up, and put it back together. That'll probably fix 90% of your issues. But while it's apart, do as I suggest with the bolt and a shell casing. On these guns, as the round is lifted by the elevator, the rim has to slide between two extractors, which are often hastily milled/fitted and rough. The back portion, to the rear of the "hook" is what I'm referring to. You'll see how it works when you have it apart.

You can likely fix it yourself. If I can, anyone can.GI6FRG1

This'll get you started
[ame]http://www.youtube.com/watch?v=oKbWcPdTRBI[/ame]
 

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It sounds like you have a model 500 tactical - not a 590A1. I have a 590A1 which has a heavy duty 20" barrel and longer magazine that will hold 7 - 2 3/4" shells. The extention goes to the end of the barrel. You would have to replace both the barrel and magazine for the match up you want I believe. The 18.5" barrels have the brace soldered farther down the barrel than the 20" models which is almost at the end. GITEN

 

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Discussion Starter · #8 ·
Hey fellas,

redlegagent, it's definitely a 590A1, it's stamped on the side of the reciever. It may be set up the way it is because it was a police gun, beats me. Either way it's being a piece of crap right now. http://www.mossberg.com/images/Mossberg_Guns/930/New/51410.jpg

I took some pics 1K, I probably only put 30 shells through it since the very first time I cleaned so it wasn't very dirty. Not sure how to pull the bolt apart but I doused it and everything else in breakfree solvent. I haven't oiled or lube and reassembled yet, nowhere around my house to really test it out... GI9

That thing sticking out of the inside of the reciever may be damaged... I'm not sure since I don't know what a good one looks like but it looks a little mangled. Also the action bars on top look a little rough, but again I have nothing to base judgement on.

Thanks for the help fellas, always helpful people on here GI6









 

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The inner piece is the ejector. It doesn't look that bad. You say it jams - how so?? Is it failure to feed - extract - eject. What part of the operation is the problem. If it's not feeding shells into the reciever properly - could be magazine spring is hung up/damaged. I wouldn't mess with the bolt beyond cleaning it or spraying some gun solvent on it. If the action bars are worn, they may not be fully catching on the bolt slide or binding. GITEN

http://www.brownells.com/.aspx/pid=0/sid=163/schematicsdetail/590__12_Gauge
 

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Discussion Starter · #10 ·
I mean it could probably use a fresh spring, that can't hurt.

I think the shells don't always come out of the tube properly secured by the elevator... maybe? It seems to jam after it's pulled a shell from the tube and it's trying to feed it into the chamber... so I guess when it's being racked forward.

And THEN last time it would chamber a shell and fail to fire. Click without the boom...

Those prongs on the bolt seem to grab shells pretty tightly if that's the kind of test 1K meant...

I had some Hornady Light Magnum short shells, they were the first ones to jam up a lot, thought it was those. Last time I took it out nothing would work correctly...

I'll put it back together tomorrow and take a video of what's going on, it's kind of late for me now... tomorrow I'll try and make some real progress.
 

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I mean it could probably use a fresh spring, that can't hurt.

I think the shells don't always come out of the tube properly secured by the elevator... maybe? It seems to jam after it's pulled a shell from the tube and it's trying to feed it into the chamber... so I guess when it's being racked forward.

And THEN last time it would chamber a shell and fail to fire. Click without the boom...
This last part could be a simple as an improperly seated barrel. With Mossbergs, it's possible to not fully seat that barrel in place, screw it down and it will action shells but not hit the primer as the shell rocks forward. I would give the magazine a good cleaning to make sure it's not binding up on something and make sure your elevator arm is okay. GITEN
 

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I mean it could probably use a fresh spring, that can't hurt.

I think the shells don't always come out of the tube properly secured by the elevator... maybe? It seems to jam after it's pulled a shell from the tube and it's trying to feed it into the chamber... so I guess when it's being racked forward.
That's what makes me think it's the same problem I experienced. I thought it must be the elevator but it turned out that polishing the flat/rearward portions of the extractors smoothed it out. The elevator simply didn't have enough leverage to overcome the friction of the extractors when the slide moves forward. It could be something else but that's an easy check. I wish you lived close and I could check it out for you.

As for the failure to fire... you got me there. ?? redlegagent's suggestion is an easy fix...

also as noted, the thing in your receiver is the ejector, and yours looks fine to me.

You do want SOME tension on the rim of the shell as the extractors grip it, but if it doesn't slip fairly easily into position, try polishing those surfaces I described until the rim springs/slips up there smoothly and the extractors grip it securely.

The interesting thing about this action is SOMETIMES the rim will slide up behind the extractor hooks when chambering, and sometimes it doesn't get captured by the extractors until fully chambered and they snap over the rim (like when you drop a slug round into the chamber and close the bolt, for example).

So if your gun has burrs/roughness/too tight extractors, it will SOMETIMES jam when chambering and sometimes it'll run fine. That's what's frustrating.
 

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A further check to confirm whether it's an extractor issue as I suspect is WHEN it jams, as the slide is moving forward and stops/jams, before you do anything else, reach under and push upward on the rear of the shell or on the elevator and see if it moves into the proper position and allows the slide to move forward and chamber.

Also double check that only ONE cartridge is released when the slide moves fully rearward... if there's something wrong with the cartridge interrupter or cartridge stop it can cause double feeding/jams. but that doesn't sound like what's happening to you.

Just as a general FYI, here's a vid discussing the 2 types of mossberg cartridge interrupters and how they work. Yours is the new type which is IMO preferable/more reliable.

[ame]http://www.youtube.com/watch?v=N0xx7-oS2OA[/ame]
 

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Discussion Starter · #14 ·
Hey guys,

I tried to address as much as I could in my 2 videos. The first one is me just showing you what the parts look like. Maybe you'll notice something is messed up. Sorry it's kind of blurry because of how close it is.
[ame]http://www.youtube.com/watch?v=0WAnkxGshAU[/ame]
I would say the second video is more informative then the first.

The second vid is the shotgun re-assembled and me test feeding it.
I put a little CLP on the spring in the bolt, not a lot. Greased the crap out of everything else. Used CLP on the trigger group. Maybe it needs a new mag spring... I don't know.
[ame]http://www.youtube.com/watch?v=Fj4XkP7prvk[/ame]

Sorry I doubt I tried everything you suggested in your most recent posts, I definitely will tomorrow.
Let me know what you think,
Thanks again.
 

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Second video more informative. First - when you reassemble the weapon, make sure the bolt is to the rear when you insert the barrel. My point is it is possible - when the bolt is forward - to not fully seat the barrel in the reciever. When you screw it down, it looks okay but if you rack the bolt back and look in the reciever, the barrel will be slightly forward. Second - many new Mossberg owners do this. Mossberg rates shell capacity on 2" shells. My gun is "rated" to hold 9 shells. It only holds 7 - 2 3/4" shells or less for all 3" magnums. If your gun is rated for 6 shells - thats 5+1 of the 2" defense shells. People will try to jam 6 - 2 3/4" into the magazine and screw it up. You shouldn't need all that grease. I would try flushing the magazine tube under hot water to flush it out and then insert a small clean rag from the reciever side into the tube (carefully DISHOUT) to swab the tube out. It looked like you were putting 3" shells into it and it was binding on the first round but worked when the spring tension was reduced on subsequent rounds. Your magazine will probably only hold 4 - 2 3/4 +1 - don't over force rounds into the magazine. GITEN

" = New. IMPORTANT NOTES: CAP: Capacity - includes one in chamber. 500 & 590 Models: one less for 3" shells. (Pending ammunition tolerance variations, total capacity may be reduced by one additional round.) "

Commercial loads range from 2" , 2 3/4", and 3" magnums. They base it on the smallest round available.
 

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Discussion Starter · #16 ·
Second video more informative. First - when you reassemble the weapon, make sure the bolt is to the rear when you insert the barrel. My point is it is possible - when the bolt is forward - to not fully seat the barrel in the reciever. When you screw it down, it looks okay but if you rack the bolt back and look in the reciever, the barrel will be slightly forward. Second - many new Mossberg owners do this. Mossberg rates shell capacity on 2" shells. My gun is "rated" to hold 9 shells. It only holds 7 - 2 3/4" shells or less for all 3" magnums. If your gun is rated for 6 shells - thats 5+1 of the 2" defense shells. People will try to jam 6 - 2 3/4" into the magazine and screw it up. You shouldn't need all that grease. I would try flushing the magazine tube under hot water to flush it out and then insert a small clean rag from the reciever side into the tube (carefully DISHOUT) to swab the tube out. It looked like you were putting 3" shells into it and it was binding on the first round but worked when the spring tension was reduced on subsequent rounds. Your magazine will probably only hold 4 - 2 3/4 +1 - don't over force rounds into the magazine. GITEN

" = New. IMPORTANT NOTES: CAP: Capacity - includes one in chamber. 500 & 590 Models: one less for 3" shells. (Pending ammunition tolerance variations, total capacity may be reduced by one additional round.) "

Commercial loads range from 2" , 2 3/4", and 3" magnums. They base it on the smallest round available.
Well I assure you they were 2"3/4 shells not 3"ers. I mean you could see in the video I fit 5 in the tube easily. I could fit 6 of the Hornady Light Magnums in it because they were smaller for some reason. I'll double check the barrel tonight to make sure it's seated properly.
Honestly I don't know how to get the magtube off or the spring out. I'll probably need channel locks or something.
 

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Well I assure you they were 2"3/4 shells not 3"ers. I mean you could see in the video I fit 5 in the tube easily. I could fit 6 of the Hornady Light Magnums in it because they were smaller for some reason. I'll double check the barrel tonight to make sure it's seated properly.
Honestly I don't know how to get the magtube off or the spring out. I'll probably need channel locks or something.
Don't try to remove the spring. Just flush it out to clean it. If you lined up different shells side by side, you will notice variations in over all length. This is due to variations in load and crimp. This is what Mossberg's statement means - variations could affect the number of shells you can load. Again, my gun is rated for 9 shells - 8+1. I can load 7 - 2 3/4" shells into my magazine with about 1.5" play remaining - not enough for another shells unless I force it in. If I mix 2 3/4" shells with 3" shells, it will reduce the number held due to size variations. If I loaded the smaller 2" personal defense loads, I could load the full 8 shells it's rated for plus 1 in the chamber for 9 total. Your gun is rated for 6 shells 5+1. You may indeed be able to get 5 shells in like you say, but if you load 4 and the 5th hangs up part of the way in - that may be all it will hold. It could be the a previous user jammed too many shells in which has caused the spring to bind inside the tube so it feeds erratically. You had trouble chambering the first round but the remaining 4 rounds chambered okay - think about it. GITEN
 

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The mag tube unscrews from the receiver in the usual direction. do NOT use chan'l'locks or any other pliers.GI8

A strap wrench might be okay. I doubt there's anything wrong with the mag tube that can't be fixed by a good cleaning, leaving it in place on the receiver. Nothing in your videos or description suggests that the mag/spring/catch/interrupter is doing anything but what it's supposed to. The spring retaining clip at the front of the mag tube comes out by just prying one side a bit, then the other, use a flat screwdriver wrapped in masking tape or something. Don't pry too much at a time or you'll bend it.

Your issue is on chambering, and I'll wager it's the problem I describe above.


Your second vid, the first round jam looked EXACTLY as described in my posts above. Do as I suggest and press upward on the elevator or the underside of the shell (before you release forward pressure on the jammed round) and see if it slides into position.

I feel like i'm saying the same things over again...GI6

I bet you a nickel if you do as I suggest your problems will be solved. It's not that hard. Get a fine diamond file/india stone or something similar and just do it. Worse case you bugger up your extractor and you have to buy another one for 4 bucks or something.


Also fyi there should be a manual focus setting on your camera, or Macro setting, so it'll be in focus when you're up really close.
 

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Discussion Starter · #19 ·
Thanks for your help fellas. It's been a little rough trying to comprehend your suggestions because I'm not very familiar with these but since I've been talking to you it's made a big difference. I'm going to mess with it more this weekend, I'll post how it goes then.
 

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Just read through the posts carefully again and let us know if you don't understand something.

To be clear; my suggestions may help with the chambering/jam issue. They will do nothing to help with the misfire issue. Making sure the barrel is fully seated might help with that, but I suspect you have either a broken/worn firing pin, a grunged up bolt/spring/pin, or MAYBE a weak hammer spring (unlikely).

also, to be very clear: if you follow my suggestions, the area that needs to be polished/cleaned up is the inside, rear face of the extractors (or hooks as you said). One on each side of the front of the bolt. Don't mess with the triangular shaped front portion or the sharp hook. The inside, rearmost face of the extractors (facing inward toward the center, the area where the rim of the cartridge has to slide up into position) is where you want to carefully file/polish. IF there's significant resistance when chambering, and it looks TO ME like that might be your problem.

You might also try some different brands of ammunition.

But a properly tuned 590 should eat just about anything.
 
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