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New 930 SPX, do I have the wrong mag spring?

Just bought a brand new 930 SPX.
I go to tear it down to clean, inspect, and lube before firing (like I do with all new guns). When I pull the mag tube extension off, the spring pops out under a crazy amount of force and flies out onto the bench tied up in a knot. It felt like it exploded.
I have taken quite a few mag springs out of shotguns over the years and have never had one that stiff or under that much tension, ever.
I measured it and it is 37.5 inches long.
I can not get this thing to go back into the tube. It wants to kink out to the side and will not compress enough to get it back in.
I am starting to think I may have the wrong spring. Could they have accidently installed a mag spring for something like the 940 JM pro with the 9+1 mag tube?
It is brand new and I have not fired it, but I feel like it might be hard, if not impossible to get all 7 rounds in the tube with that stiff of a spring (if I can manage to get it back in).

I have a 2nd identical 930 SPX I bought used (fixing to sell it) and the mag spring in it is only 27 inches long. I have no history on it and no clue how old it is, but I just have to guide the spring a little and it goes back in with no fuss. No loading or feeding issues with it, holds the full 7 rounds no issue.
 
Anything is possible. 37 inches sounds long to me too. That's nearly as long as the whole gun.

If you think it's too much, start cutting some coils off.
 
I would function-test it before making any mods. Firstly, see IF it will take 7 in the tube. You might make a special "tool" out of PVC pipe to help keep the spring from bending as you insert into the tube. Cut it lengthwise so if forms a "C" cross-section.

It is quite possible you got the wrong spring from the factory, or it has been "revised" to be longer to avoid FTF issues.

Has the "old" 930 spring been cut?
 
Generally I cut springs to 12" longer than the mag tube OAL and trim if needed.

Even at this length its a pain to get back in the tube.
 
I had more time this afternoon to mess with it when I got home from work.
After a lot of cussing, I finally was able the spring back in, but it was a total pain in the butt. I failed 3-4 times before finally getting it. I had to use two fingers on my left hand to hold the spring in the tube while using my right hand to push it in one coil at a time, getting harder and harder to do with each coil.
Once I got it back in, I tested it and I was able to get all 7 rounds in it. It was a little stiff to load, but not overly hard.
I will hopefully have time to shoot it this weekend.
I am tempted to load 7 shells in the mag and let it set fully loaded for a week or two to try and break in the spring a little.

I checked the old SPX and it does not look to have been cut. Both ends look the same and look just like the ends of the new spring (coiled to create a "end")
The coils on the new spring are much further apart than the old one.
 
If you have the Choate extension (I believe Wilson & a couple of others do this as well) there is a small hole in the end of the tube-it's for a .22/.223 cleaning rod. Dropping that in from the top will help keep the spring from snaking up.
 
Yea the end of the tube extension has the rubber plug with choate on it.
Interesting idea on using a cleaning rod to help keep it somewhat lined up. I will have to try that when I clean it after shooting it this weekend.
I always told the holes were to allow water a way to drain out if any ever got in there.
 
Give Mossy service a quick call to ask them about the spring length. If it’s not correct they will probably send you a new one. You could also test the spring from the used gun in the new gun to see if there is a difference. Good luck!
 
Yea the end of the tube extension has the rubber plug with choate on it.
Interesting idea on using a cleaning rod to help keep it somewhat lined up. I will have to try that when I clean it after shooting it this weekend.
I always told the holes were to allow water a way to drain out if any ever got in there.
That too, but this primarily. Old service Remingtons from the Viet Nam era have them- it does help drain, but kinking your mag spring 2000 miles from anyplace not the bottom of an outhouse rates as a very low point in life.
 
Got to shoot it today.
I started out with a 25 round box of S&B 12 pellet 00 buck I found (forgot I had it).
I started out with just 5 rounds cause I put the first couple on paper just to see where it hit (maybe a touch high at 25 yards) but the pattern on this ammo was so large it was hard to really tell.
I had one failure to feed. The round was half way in the chamber. A light bump of the charging handle and it went in no issue.
I then loaded a full 7+1 rounds and had one more failure to feed (just bumped the charging handle again). But all others were fine.
I then fired 5 rounds of rem slugger 1oz slugs with no issue.
I then go to load the mag and could only get 5 rounds in it. It was like the rounds were hitting a brick wall.
I shot all of them with no issues. I try to load up the mag again and still only got 5 rounds, but I just kept trying and after pushing and releasing the shell a few times, I felt something give/pop, and then it took the other two just fine.
All those fired just fine. I go to load again and back to 5 rounds.
I go get the older used 930 and took the shorter mag spring out of it and put it in the new one.
I had no more issue loading the full 7 rounds in the mag.
I fired another 25 rounds of some 8 pellet 000 buckshot (my reloads) and had zero issues. all cycled just fine and I could load the full mag tube just fine.

Other than the two failures to feed in the first few rounds, I had no other feeding or cycling issues. Just the mag issue.
I wonder if the super long/stiff spring is kinking/binding inside the tube? Once I swapped to the older short spring, I did not have any issues loading it to capacity.

I tore it down and cleaned it, and cleaned the chamber with a old bore brush wrapped with a little 0000 steel wool and some bore cleaner. It looks way better now and feels smoother. That might have been the issue on the couple failures to feed.
 
First, do call Mossberg.

I’ve never messed with a 930, but my second advice would be make absolutely sure you have no rust in the mag tube. My 500 had rust in the tube from the factory.

Also what kind of follower do you have?

I had one with an orange plastic follower that would swell up from certain gun care products, causing failure to feed.
 
No rust in the mag tube. I cleaned it out the mag tube when I did the original teardown and clean/lube when I bought it.
The follower is the factory metal follower.
I will try and get some time this week to give them a call and see what they have to say.
 
Watched the video, lots of rambling on and on for not much info.
I know what plug he is talking about, but it is not a 5 round limiter. It is way too short for that. I have seen in other threads people are saying it is to protect the plastic cap of the mag extension from the spring.

I tried calling mossberg on my lunch one day but got put on hold and I ran out of time before I got to anyone. Have not had a chance to try again.

I played around with it some tonight when I got home from work.

With the older/shorter mag spring, it seems to take all 7 shells no issue.
With the spring that came with it (the long one), about half the time, it will only take 5. It is like it is against a brick wall. I think the follower is hanging up on the transition between the mag tube and the extension. My guess is the long stiff spring might be causing the follower to tilt in the mag tube slightly and causing it to hang up. While the shorter old spring, being not as stiff, is not putting so much pressure on it and letting it stay more straight.

I found with the plastic plug on the end of the spring, you can fit 7 normal length shells in it, but there is not a hair of room left. If you had any shells that were slightly longer than normal, you would only get 6.
Take the plug out, and it will take 7 normal length shells with a little room to spare before the spring bottoms out.
Is it enough to be able to get that 7th round of slightly longer than normal shells in it? I do not know, as all mine are the same/normal length.

For the hell of it, I ordered a NDZ follower when I ordered one of their metal safeties. I have them in two other mosbergs with no issues and really like them.
I put it in the 930 and it will take all 7 rounds, but , it seems to hang on the way back down and stops feeding about half the time. So I put the original one back in.
I compared the old mag extension to the new one. The new one has had the inlet slightly tapered, where the old one does not. Looks like they know about the follower catching on the extension and have tried to take some steps to make it smoother. Just looks like it is not completely worked out yet.
All the tests done tonight was just loading and unloading my hand. No live fire. I would load, then then unload using the slide release. I never once chambered a round during these tests.
I will try and do some more shooting this weekend.

Will try and continue to call mossberg also.
 
My opinion for what it’s worth. If you “hit a wall” at 5 rounds it’s not a spring problem. The follower is getting hung up on a surface that prohibits it from moving. The stock mossy follower is what it is. In one of my M930 shotguns it performed better than an aftermarket. I do not have any extensions on my 2 mossy 930’s.
Call Mossy service and get them to confirm the spring length. If they send you a new one great. You can cut down the other one to suit and have a spare.
 
Mossberg service does not have any demonstrable, functional, knowledge about their firearms. As noted, an aftermarket follower with front and rear chafers, in addition to increasing the chamfer in your extension tube where the threads step to the smaller tube diameter, is most likely to solve your issues.
 
As a metalworker, I often use what is called a "hand deburr tool". I like NOGA brand but also have some Shaviv handles (I think). The first pic shows the handle and tip I probably used at least once today. The second pic is of an assortment to show some of the different tips you can buy. You run the cutting edge of the tool along the sharp edge of a flat or hole and it "carves" a thin sliver of metal from the edge, chamferring it. You can make multiple passes to remove more material...

R.jpg OIP.jpg
 
Got some time to fiddle around with it this morning.
I swapped the mag springs between the older used one and the new one.
The new one loads and functioned 100% normally with the shorter spring from the older used gun.
I put 75 rounds through it this afternoon with zero issues. Loaded to full capacity every time with no problem.
I did 25 rounds of 000 buckshot I handloaded, 25 rounds of federal field and target 1200fps (that comes in the 100 round value packs), and 25 rounds of win AA 1145 fps.
Every single one cycled perfectly and not a single hiccup.

The older used gun, with the longer stiffer mag spring from the new gun in it, loads and functions perfectly fine. No issues loading to capacity and no issues cycling either.

So as far as I am concerned, I am gonna leave it be. It now functions perfectly fine with the older spring, and other older gun functions fine with the newer spring.

I did finally get mossberg on the phone thursday. He needed my SN before he would help me. So I wrote it down and called back friday and they were closed for some company picnic. At this point I have given up on them. The issue seems like it is fixed now.
 
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