Mossberg 930 JM Pro Disappointment. Anyone Else?

[YZFNYC]

Ok, So about 2 weeks ago I finally got my hands on the Mossberg 930 JM Pro I had been wanting for about a year. I took it home and was going to clean it but when I cleared the checked the bolt and let it close it was near impossible to open. I finally opened it with some brute force and was able to clean a bit but not able to take of the barrel so could not clean it throughly. I took it back to Turners where they said that it just needed a lot of cleaning and that it had been probably fired a lot. I was like its new how could that be? I know they fire a round for function but apparently they shot mine a lot to get it to function correctly. Took it home and with some brake cleaner and some WD40 was finally able to loosen the barrel off and take a look. Appears that they force it in and pinched a gasket of some type. See Below:



The black one seen below was stick out of the groove it was suppose to be in . Cleaned the Shotgun and then tried to get it back together holy *****. Had to go get my rubber mallet and pound the barrel back in thru the gasket. Wouldn't work. Used a motorcycle axle that I had laying around to force the gasket in a little more then it was and got the barrel in with a couple of mallet hits. then took it out again and got it back in normally. Hoping that it will work properly when I finally use it.

It was really dirty and had marks around the barrel as if they took a vise or something to it. Since you can't return firearms I'm stuck with it but I find it annoying and wanted to see if anyone else had they issues with their Mossbergs. Its my first and nothing like the finish quality of S&W, Colt or Ruger firearms.


Marks on Barrel


Some lead deposits and a little bit of rust. Yes on a new firearm.


Yes that be rust. Cleaned it and added a little paint to protect it.


No idea what that is but had lots of lead deposits this is after cleaning once already.


More dried up lube/grease


Bolt face after a few cleaning. Marred on the face as you can see. Would not come off.


Ejector full of lead/carbon deposits.


underside of bolt after cleaning and still the dry grease won't come out.



Back together again.

[helixultra]

That sucks. I bought a jm pro brand new and sold it without even firing it. I have a benelli m2 tactical and the quality is way much better. Buy once and cry once.

[kdruff2]

Sorry if I missed this earlier, but you bought it new correct?

If so, shouldn't it be under warranty from Mossberg? What am missing here?

Either way, super bummer.

[awiner]

See comments below in red..... Also, check out http://www.mossbergowners.com/index.php for a TON of good info.

This is a known issue with the 930's. As you found out, centering the spring and associated parts was needed. If this continues, you will start to notice gauge marks on your mag tube.



These are factory roll marks to indicate various stages of QC (or lack thereof)





Thats crazy. My two 930's did not have rust but I could tell they had been test fired due to the normal evidence of such.



This is your piston assembly. After use the chrome piston will become discolored. Not much you can do about it. Strip the gas rings off of the piston assembly and clean them well too.



That is not grease. It is red loctite used to keep the mag tube securely in the receiver.



Never seen wear like this.....



Evidence of firing



The firing pin is coated in a red type of 'paint'. Not grease.

[SuperSet]

Sorry you're having trouble. As to the rust being on the weapon, I can't believe that Turner's didn't make this right with you. That's bad customer service.
More generally, Mossberg QC is hit or miss. I had a 930 that ran pretty well though it didn't shoot slugs worth a damn. My buddy's 930 is a jam-o-matic. There are several 930JMs floating around among my shooter buddies and they seem to be running fine, although you need to religiously keep the piston clean.
Good luck!

[YZFNYC]

Thanks for the feedback guys, As always I can count on the Calguns people to look out.

"kdruff2" Yep, this was brand spanking new allegedly, So your not missing a thing.

"awiner" thanks for the comments. Glad they used loctite at least. You said "Strip the gas rings off of the piston assembly and clean them well too." is that the part that spins? If so how do I get that out? Didn't see that in the instructions? It's my first shotgun so just going off general Rifle/Handgun knowledge. Sorry...

"SuperSet" The Turner's Guy asked how many shells I put through it? I said none its new. was trying to do the first cleaning and the bolt got stuck and the barrel won't come out. He said well its "gunked" up good it should come out if you clean it well. Took it home and got the Gunk Brake Cleaner out and de-gunked. lol... Got the barrel out with a lil Brake Cleaner and WD40... I <3 WD40. Is it safe for firearms? Doubt brake cleaner is but no harm no foul. Right? Going to try to take it to the Range in El Monte this weekend hope all works! Fingers Crossed.

[awiner]

"awiner" thanks for the comments. Glad they used loctite at least. You said "Strip the gas rings off of the piston assembly and clean them well too." is that the part that spins? If so how do I get that out? Didn't see that in the instructions? It's my first shotgun so just going off general Rifle/Handgun knowledge. Sorry...

Yes the spinning rings on the piston are the gas rings. This is where a lot of the carbon will build up.

See the video here: http://www.youtube.com/watch?v=6oW1wJis9LY

Make sure to note the orientation for reassembly. The chamfered sides face outward. Make sure when installing the piston that the gas rings are staggered. One slit across from the other slit. This will aid in lower fps shot cycling.

Make sure to run the bolt and slide on the wet side and the piston assembly very lightly oiled.

The 930 is a great gun that needs a proper break in with 1200fps+ loads. In many cases to run reliably it will also need some 'tuning' (sometimes the shell stop needs to be polished for reliable function -- You may also have to trim your marginalize spring if you have feed issues).

Another thing I recommend is that you should back the Nordic Clamp magazine tube extension off just a hair before tightening down the Nordic Clamp barrel/tube clamp.

As I pointed out above, http://www.mossbergowners.com/index.php is an invaluable resource.

[YZFNYC]

Thanks for the heads up on the maintenance and care of the Shotgun. I'll try it out at the range if I can make it out sometime this weekend. I'll update once I do that. Just got a little rattled by the fitting and condition of it since I waited so long for the model, heard so much positive reviews for this model and then for it to not even be put together correctly from the factory is a little bit of a worry and since Its my first shotgun its not like I can compare and see what might have been the issue. Just hoping nothing but the targets blow up. Thanks again to all who gave me their two cents. Yah the best!

Yes the spinning rings on the piston are the gas rings. This is where a lot of the carbon will build up.

See the video here: http://www.youtube.com/watch?v=6oW1wJis9LY

Make sure to note the orientation for reassembly. The chamfered sides face outward. Make sure when installing the piston that the gas rings are staggered. One slit across from the other slit. This will aid in lower fps shot cycling.

Make sure to run the bolt and slide on the wet side and the piston assembly very lightly oiled.

The 930 is a great gun that needs a proper break in with 1200fps+ loads. In many cases to run reliably it will also need some 'tuning' (sometimes the shell stop needs to be polished for reliable function -- You may also have to trim your marginalize spring if you have feed issues).

Another thing I recommend is that you should back the Nordic Clamp magazine tube extension off just a hair before tightening down the Nordic Clamp barrel/tube clamp.

As I pointed out above, http://www.mossbergowners.com/index.php is an invaluable resource.

[awiner]

Let us know how it goes. If your looking for a pistol grip for the JM Pro, I just put one I had up in the for sale section.

[MongooseV8]

I have the 22" version of the JM Pro and I have run about 100 rounds through it so far. Its a great entry level shotgun and I have not had the same problems with mine. I bet after you get some rounds through it everything will be fine.

[awiner]

The biggest issue most have with the 930 is getting the magazine tube spring cut to the correct length.

Mossberg may have supplied the JM Pro's with the correct length spring but on on 18" 930's (SPX) with the +3 magazine extension there are all kinds of spring lengths in the wild.

I had to cut 5-6" inches off my spring in order to get a full magazine tube to release the first shell in a reliable manner.

The factory spring was so long (38") before cutting that it put way too much spring tension on the shell stop and wouldn't allow the first round from a full mag tube to release on the elevator.

[YZFNYC]

Ok, well got to take her out and run 50 rounds of Wolf Power 1 oz Rifled Slug at an LA Gun Club [indoor range] because I didn't get a chance to take her skeet shooting this weekend because of Chinese New Year and Superbowl.

The issues continued. 1st issue was that it won't load more then 4 rounds in the magazine tube so 5 total with the one in the chamber. Also the last round would get hung up with the feed ramp every single time. I'm pretty sure its that seal that I saw was not properly seated and that I got to move sorta into place. I am very disappointed to say the least. Haven't cleaned it since I just got back from the gun club I will clean it tomorrow and see what is going on and if I can't get that seal to seat itself take it to my local gunsmith Bain & Davis and see if they can do something. If that don't work I'll take it back to Turners so that they can return it to Mossberg for repairs.

Other then that the rounds that actually left the shotgun were fairly accurate and the kick is less then what I felt shooting an AR-10 so if they had done it right with good craftsmanship and attention to detail and OA was done I might have been a happy camper. Now I just feel let down.

[anti]

Definitely take it to Turner's... you paid for a NEW shotgun and deserve one that functions properly and isn't caked with crap. Makes me wonder if someone at the store took it out to have some fun themselves.

[aippi]

Break and parts cleaner is fine for firearms. I use cases of Cyclo Break and parts cleaner a month in my gun shop. The can is twice the size of "gun Blast and half the cost. Same stuff. But get the non-flammable kind.

[vintagedude88]

Ok, well got to take her out and run 50 rounds of Wolf Power 1 oz Rifled Slug at an LA Gun Club [indoor range] because I didn't get a chance to take her skeet shooting this weekend because of Chinese New Year and Superbowl.

The issues continued. 1st issue was that it won't load more then 4 rounds in the magazine tube so 5 total with the one in the chamber. Also the last round would get hung up with the feed ramp every single time. I'm pretty sure its that seal that I saw was not properly seated and that I got to move sorta into place. I am very disappointed to say the least. Haven't cleaned it since I just got back from the gun club I will clean it tomorrow and see what is going on and if I can't get that seal to seat itself take it to my local gunsmith Bain & Davis and see if they can do something. If that don't work I'll take it back to Turners so that they can return it to Mossberg for repairs.

Other then that the rounds that actually left the shotgun were fairly accurate and the kick is less then what I felt shooting an AR-10 so if they had done it right with good craftsmanship and attention to detail and OA was done I might have been a happy camper. Now I just feel let down.

Did you disassemble the mag tube to check the spring? Also check to see if there is a wooden dowel in the tube to limit your capacity. The Nordic mag tube extension has a slightly larger ID than the Mossberg tube ID. The stock follower has a very sharp edge on it that needs to be chamfered. The front edge of the stock tube is also sharp and needs to be chamfered as well on the inside. Once that is done, lube the follower generously and feed rounds in to check. Cycle those rounds also and make sure they all chamber and extract correctly.

Lastly, when you first got your gun did you tear it down completely to clean and relube? I've been told that Mossberg only applies rust inhibitor before leaving the factory. You need to clean off the rust inhibitor and apply fresh lube before taking it to the range.

Once you do that your only worries would be how to feed it.

BTW, 1300 & 1400 FPS slugs are okay. However 1600 FPS slugs Winchesters from Walmart....OUCH! (My personal experience)