mossberg 590A1 questions

[strongpoint]

hi, shotgun people -- i just bought my first, a slightly used 20" mossberg 590A1 from a fellow calgunner. it'll be used primarily for home defense (the wife is eager to learn) and showing range targets who's boss, but of course one never knows when a scattergun may come in handy.

i got it out of 10-day jail last week and haven't had a chance to take it to the range, but i did partially strip it for cleaning and inspection (i pulled the barrel and trigger group, and i got the cartridge stop and interrupter out, but i stopped before pulling the bolt and elevator, and i don't have a wrench for the forearm). a few questions came up as a result. i can post pics to illustrate, if need be.

1) it did not come with a forward sling swivel. i bought one for the hole in the back of the bayonet lug, which is where i'd rather mount the sling, but the magazine cap is also drilled and tapped for the same type of swivel. should i plug that hole, even if it's just for the sake of weatherproofing?

2) no choke. problem?

3) how does one determine whether the barrel (marked "590," not "590A1") is indeed the heavier model?

4) the instruction manual and various disassembly guides warn that the magazine spring is under significant pressure and that caution is required when removing the mag cap. i was duly cautious, but the spring appeared to be under virtually NO pressure -- i removed the mag cap and it went nowhere, though it does extend out of the tube by an inch or two, and it does put light but definite pressure on the follower. problem?

5) possibly related: there was no mag spring retainer anywhere in sight, just the spring sitting against the inside of the mag cap. problem?

6) there's a small crimp at the end of the mag tube, but it doesn't affect installation of the cap as long as you're aware of it and push the cap past it to make contact with the threads on the tube. problem?

7) the thing was fairly dirty on the inside when i got it, covered in a sort of tacky grime. i cleaned everything accessible on the exterior (though i'd like to get under the forearm), as well as the bore and some of the internals. is this normal? should i clean and re-grease the outside of the bolt and trigger group? how about the inside of the mag tube -- and is it worth removing the tube?

8) finding a forearm wrench -- there are lots of models out there listed as working with remington 870s and mossberg 500s. are these compatible with this model?

9) finally (jeez! he goes on forever!), i'd like to replace the safety switch with an aftermarket model with more traction. how the heck should i go after that one-way anti-tamper screw that secures the existing switch?

sorry for the long post. thanks in advance, felllow calgunners.

[G-forceJunkie]

1) I would put one in there just to plug the hole, but its not an issue either way.
2)Not a problem, for its intended purpose. you should pattern it a various ranges so you know the spread of your prefered ammo.
3) Without having one sided by side to compare, you could measure it. I had both models at one time, IIRC the heavy barrel was at least twice as thick at the muzzle.
4)Mag springs do take a set over time. You can buy upgraded ones. The poormans fix is to just strech it out a bit if its starts giving you problems. Its a tempory fix but it would get you through your day of shooting.
5)Neither of mine came with retainers, just the end caps holding the springs in.
6)As long as the pinch does not interfere with the movement of the spring or follower, you fine.
7) It sounds like whatever it was lubed with before gets sticky when it dries up. Give it a good cleaning and lube with oil, I like CLP, I've never had an issue with stickyness. It just gets dirty with fowling. I always pull the mag spring and follower and push a cleaning patch through. Then, leave it dry upon reassembly.
8) most things listed for a mossberg 500 will work with a 590. But I'm not sure you need a forearm wrench unless you plan on removing the grip? Usually just slide it off the tube with the action bars hanging on it and clean as is.
9)No idea, never had an issue with the stock on. Perhaps give it a fair trial before messing with it?

[inbox485]

hi, shotgun people -- i just bought my first, a slightly used 20" mossberg 590A1 from a fellow calgunner. it'll be used primarily for home defense (the wife is eager to learn) and showing range targets who's boss, but of course one never knows when a scattergun may come in handy.

i got it out of 10-day jail last week and haven't had a chance to take it to the range, but i did partially strip it for cleaning and inspection (i pulled the barrel and trigger group, and i got the cartridge stop and interrupter out, but i stopped before pulling the bolt and elevator, and i don't have a wrench for the forearm). a few questions came up as a result. i can post pics to illustrate, if need be.

1) it did not come with a forward sling swivel. i bought one for the hole in the back of the bayonet lug, which is where i'd rather mount the sling, but the magazine cap is also drilled and tapped for the same type of swivel. should i plug that hole, even if it's just for the sake of weatherproofing?

Plug if you want. Don't if you don't. Never made any functional difference on mine. Any condition that would get water in that little hole is going to get water up the barrel also.

2) no choke. problem?

No choke is the norm for HD although IC and Mod chokes are increasingly common. At common HD ranges the choke will not make a measurable difference. Having no choke is fine, but not knowing how wide the pattern will be is not. If you have never been to a formal training class, you should, and patterning is always part of the shotgun classes. Every barrel patterns every different load a little bit differently. In my experience it also changes a little with the life of the barrel so re patterning a the beginning of range trips is wise both for confirmation and as a reminder.

3) how does one determine whether the barrel (marked "590," not "590A1") is indeed the heavier model?

Side by side the A1 barrel is thicker, and heavier, and the Mossberg barrel shroud won't fit without modifications. I don't recall special markings on it. Do keep in mind though that a lot of 590 accessories that interface with the barrel won't work on both.

4) the instruction manual and various disassembly guides warn that the magazine spring is under significant pressure and that caution is required when removing the mag cap. i was duly cautious, but the spring appeared to be under virtually NO pressure -- i removed the mag cap and it went nowhere, though it does extend out of the tube by an inch or two, and it does put light but definite pressure on the follower. problem?

No. Brand new the mag spring is about 8" longer than the tube, but shinks to about 2" longer than the tube the first few times it is fully loaded. The cap will however be under a butt load of pressure if there are shells in the tube (which would be a no no anyway).

5) possibly related: there was no mag spring retainer anywhere in sight, just the spring sitting against the inside of the mag cap. problem?

No. The previous owner probably took it out. They tend to deform the tube such that the threads don't play nice (you have to use the cap to press the retainer in place). All in all, you are better off without it.

6) there's a small crimp at the end of the mag tube, but it doesn't affect installation of the cap as long as you're aware of it and push the cap past it to make contact with the threads on the tube. problem?

I don't think I've seen that before but if the cap threads on, and holds the barrel firmly in place, you are good to go. The crimp could have been caused by the last owner trying to get the stupid retainer cap to fit right.

7) the thing was fairly dirty on the inside when i got it, covered in a sort of tacky grime. i cleaned everything accessible on the exterior (though i'd like to get under the forearm), as well as the bore and some of the internals. is this normal? should i clean and re-grease the outside of the bolt and trigger group? how about the inside of the mag tube -- and is it worth removing the tube?

Sounds like the last owner left the packing grease in place. Yes you want to strip clean and re-oil everything. The packing grease will get gummier with use. Out of the box, Mossbergs look like they were slathered in vasoline, diped in used motor oil, and tossed in a dirt pile. They need a thourough cleaning. Auto parts cleaner works wonders.

8) finding a forearm wrench -- there are lots of models out there listed as working with remington 870s and mossberg 500s. are these compatible with this model?

AFAIK, yes, but I just used a metal piece I had laying around the garage.

9) finally (jeez! he goes on forever!), i'd like to replace the safety switch with an aftermarket model with more traction. how the heck should i go after that one-way anti-tamper screw that secures the existing switch?

sorry for the long post. thanks in advance, felllow calgunners.

Generally a flat head screw driver works if you press down nice and hard. If not, I've herd of people using a striped bolt extractor.

[strongpoint]

thanks for the good advice, guys (i assume).

G-forceJunkie, i felt like the existing safety gave me a little less traction than i'd like on such a crucial control. inbox485 gave me inspiration for an idea -- if you place the screwdriver so the blades are a little way up the ramp that makes the screw head anti-tamper, some light hammer taps on the end of the screwdriver will edge the screw counterclockwise. once it was loose enough, i was able to get it out with regular use of the driver and install the aftermarket replacement, which feels much more solid under my thumb.

inbox, i'll bet that crimp at the end of the mag tube was caused by the previous owner trying to get something out of the tube (retainer? follower?) with a set of longnose pliers.

i stripped it fully today -- including the bolt and forearm -- cleaned it and regreased everything, and put it back together. it passes function tests fine and appears to rack a little easier now. range time is next on the agenda.

i'm just leaving this here so i can find it later (unless someone knows proper dimensions for normal vs. heavy barrel): at the muzzle, the barrel is about 0.0935" OD, 0.727" ID, and 0.109" thick.