Jump to content
Brian Enos's Forums... Maku mozo!

930 JM Pro jams/won't cycle slugs or buckshot


bullpup
 Share

Recommended Posts

I got my lifter back from c-rums yesterday and put my gun back together. Took it out today and it will cycle birdshot but it won't cylce full power slugs or buckshot, both were remington. The shells aren't coming out of the magazine. The only other thing I have done is change the magazine spring out to a shortened Nordic spring. Before the spring and lifter were changed it would cycle everything. Any help would be appreciated.

BP

Update: Shot the gun again today and I noticed that the gun is actually jamming. It's like the lifter is getting above the shell catch latch. This only does this with buck or slugs. The shell ejects but a new one doesn't come out of the magazine and this is what it looks like when it happens. Also I'm getting a wierd wear mark on the front of the trigger group. It looks like the bolt catch is rubbing against it. Any ideas?

IMG_0712_zps4a923507.jpg

IMG_0711_zps727eb532.jpg

IMG_0720_zps30c27cc7.jpg

Edited by bullpup
Link to comment
Share on other sites

The only other thing I have done is change the magazine spring out to a shortened Nordic spring. Before the spring and lifter were changed it would cycle everything. Any help would be appreciated.

BP

I can't explalin the birdshot yes and the buckshot no, but if you cut the mag spring too short, there may not be enough spring pressure to feed shells from the magazine.

Just a theory, but the mag spring may be sufficent to keep up with the lower power shells, but not enough to keep pace with the full power loads.

The mag spring should have, and this point is certainly an arguable one, about 13" or better of free length past the mag tube with the mag end cap removed.

C

Edited by creeper1956
Link to comment
Share on other sites

I had the same issue it was the piston parts. Once they get fouled the gun stops running. Also with slugs and buck I found it really likes having a solid stance, it seams like if you are limp with your stance when using the higher power stuff if can jam. Once you get the piston out you have to take it apart completely and then get everything cleaned and lubed so it moves smooth and free. In fact I ended up polishing most of the parts for better performance. If you stay up on the maint the gun will run great. I found out the hard way during a local match.

Link to comment
Share on other sites

My money is on your mag spring is too short. I've been bit a couple times with my M2 by cutting it too short. Now I cut it almost as long as I can and still get the full mag capacity. I'm guessing what is happening in your case is with the heavy loads your gun has more rearward momentum while the spring is trying to push in the same direction, thus hampering it's ability to push the next shell onto the lifter. Is it happening on all your shots or just the last 1 or 2 in the mag? What Dave said about the piston system is solid advice too.

Link to comment
Share on other sites

I did clean the shotgun and put it away before I sent the lifter off. By the way, the lifter turned out awesome! This would make me think it is the spring as well unless I put something back together wrong. I did load the magazine full of shells and shot it and it still had the malfunction pictured. Thanks again for all of the advice. I'll put the stock spring back in a try it out.

Link to comment
Share on other sites

Let me be the dissenting opinion: It's the recoil not operating the bolt strongly enough. There's a bug in the 930 that if you drop the bolt with the bolt release but only do it lightly, the lifter jams on one side in the position you show. Hit the release hard and it will drop properly. Empty the gun and try it, just tap the release hard enough to let the bolt go and see if you can't duplicate the error. I don't have a fix for it yet but from looking at it I think there's an area on the lifter that could be relieved. I've mostly just trained myself out of it but I've been using full power ammo. If it were to start doing it on recoil rather than manual operation then it must be fixed, now.

Link to comment
Share on other sites

I've seen the same issue, lifter get "wedged" when the gun short stroked. What fixed it for me was the detail cleaning outlined above.

Bullpup, I know you said you cleaned it but did you detail strip the piston. I think that can break down into 3-4 pieces. All of those pieces should rotate freely and smooth, the when assembled the piston should move free and smooth once installed back on the tube in the barrel piece. Someday ill make a video as the one out there that detail strips is kinda hard to follow/see. Also sometimes the gas ports need cleaning too.

Link to comment
Share on other sites

My experience is identical to the OP on my out of the box JM Pro. Its boxed up to go back to Mossberg. Any other suggestions? I have completely cleaned the piston as detailed above and it is still jamming the lifter above the bolt release exactly as pictured above.

Link to comment
Share on other sites

Thanks everyone for all of the suggestions. I've ordered a new mag spring, and I'll also take it apart again and make sure everything is really clean. I'm really thinking that it has to be the mag spring because it is the only thing that I've really changed besides the lifter. I've had it for about a year and it has been flawless until now.

Link to comment
Share on other sites

I too have the issue that has been outlined above. I have one more thing that may be worth looking into. I was at my gunsmith the other day and we were checking the gun out. I have the 22" jm pro . His only other thought was that it was related to the shell stop at the mouth of the magazine tube . Being that it may not be smooth enough or slightly too large to let the shell pass over it at times . I"m going to be taking it in this week and we're going to mess around with polishing it . I'll post again if it changes anything .

ps. fun fact , this gun has been back to mossberg 2x

Edited by thegunnerd
Link to comment
Share on other sites

I had to polish the shell stop, and lightly break the corners to keep it from hanging up on the shells and preventing them from popping out onto the carrier. Only a problem with a full tube for me.

I just polished mine today , gonna take it to the range as soon as i can and see if that's the fix.

Link to comment
Share on other sites

Well I put a new spring in it and cut it to 14 inches. Went and shot and it still does the same thing 80% of the time. Bird shot is still 100% I even mixed different types of birdshot, low recoil 8 shot and regular walmart federal. Still ran 100%. I mixed and matched slugs, buck and bird. Still had very little effect on working, especially with slugs. So now that I have eleminated the spring I will take it apart again and make sure I have thoroughly cleaned everything. Maybe there was something I missed last time. I may also polish the shell stop while I have the gun apart. I guess if the cleaning and polishing doesn't fix the problem, my only other theory is that the welded up lifter has added enough mass that it is interfering with the timing. Thanks again for all of the ideas and suggestions.

BP

Link to comment
Share on other sites

Is this a problem with just the JM Pro's?

The only problem I have w my turkey(Open) 930 is too much mag spring pressure will not allow a shell to release properly from the tube.

I know messing with the release spring pressure causes problems when just hand cycling and may look like those stated above when fired?

I hear from Mark Roth(X-Rail) all the time to keep the release area well lubed.

If I had to guess at the 3(just in this post?) different JM's w same issue that it is something to do with the release lever spring pressure being too high or something on the inside of the receiver is causing friction on the lever during cycling heavier rounds maybe due to flexing of the receiver itself.

Maybe the lever is just a little too tight a fit in it's channel on the receiver?

Keep in mind this is just a theory and nobody should start modifying their stuff.

Nick

Link to comment
Share on other sites

Well I put a new spring in it and cut it to 14 inches. Went and shot and it still does the same thing 80% of the time. Bird shot is still 100% I even mixed different types of birdshot, low recoil 8 shot and regular walmart federal. Still ran 100%. I mixed and matched slugs, buck and bird. Still had very little effect on working, especially with slugs. So now that I have eleminated the spring I will take it apart again and make sure I have thoroughly cleaned everything. Maybe there was something I missed last time. I may also polish the shell stop while I have the gun apart. I guess if the cleaning and polishing doesn't fix the problem, my only other theory is that the welded up lifter has added enough mass that it is interfering with the timing. Thanks again for all of the ideas and suggestions.

BP

I don't think it's your welded lifter because I have a similar issue with an unmodded lifter . I have yet to test mine after polishing the shell stop , I'm hoping to get to the range tomorrow , I'll post if it improves

Link to comment
Share on other sites

I had some issues with my JM when I first received it, but I did buy mine gently used from someone on this forum. I know that most everyone just wants their gun, that they paid good money for, to work, but sometimes what we ask of our gear is more than the factory planned.

All that said, I sent mine to Benny's team at Triangle and havent had a single hiccup out of it since (knocking on wood). Not sure they are still working on 930's, but if they are, they can probably get you squared away.

Link to comment
Share on other sites

Fastshooter 03. Here's the path, sorry it's so long, to my article on polishing the shell latch. If it won't release rounds with a full tube, this fixed it. http://www.brownells.com/.aspx/lid=15831/GunTechdetail/Fixing-A-Mossberg-930-Feed-From-The-Tube-Problem?sp_rid=MjM5MzI1MTM5MDYS1&sp_mid=4574276&spMailingID=4574276&spUserID=MjM5MzI1MTM5MDYS1&spJobID=133893907&spReportId=MTMzODkzOTA3S0

Talking with someone about welding lifters causing problems because of extra weight - he completely dispelled that when he said, "it works when lifting a 1 oz shell and a 1-1/4 or 1-1/2 oz shell, the little bit you ad welding it up is far less than 1/4 oz. You have something else wrong." Made sense to me.

Link to comment
Share on other sites

Fastshooter 03. Here's the path, sorry it's so long, to my article on polishing the shell latch. If it won't release rounds with a full tube, this fixed it. http://www.brownells...=MTMzODkzOTA3S0

Talking with someone about welding lifters causing problems because of extra weight - he completely dispelled that when he said, "it works when lifting a 1 oz shell and a 1-1/4 or 1-1/2 oz shell, the little bit you ad welding it up is far less than 1/4 oz. You have something else wrong." Made sense to me.

Thanks Larry,

Nick

Link to comment
Share on other sites

Cleaned the shotgun again and polished the shell stop. I also ordered some Rio Low Recoil buck and it came in the mail yesterday. I took the gun out this afternoon and shot it. It will run with the Rio LR buck and it will now also run with the Winchester green hull military buck. It will not run with the Remington buck or with Remington slugs. I only had two rounds of Winchester slugs left and it did run those. Not much of a test with the slugs, so I need to get a couple more brands to see if I can find one that will work. At least I found that it will run the Rio LR buck so I will just buy that from now on. Still have to do a little more work with the slugs. I'm not sure if it was the cleaning or the polishing or if either helped. My gut tells me that it would have run the LR buck anyway since it will run birdshot 100% of the time. Any other thoughts. I'm happy as of now. Just a little perplexed. I'll get some more slugs, maybe order some LR slugs, and hopefully find some that will run well. Thanks again for all of the help.

BP

Link to comment
Share on other sites

BP

Try the Fiocchi low recoil slugs. I had the same issue with some full recoil slugs like the rem, and my gun likes the Fiocchi a lot. But only the low recoil slugs, my gun had issues ejecting the Fiocchi i think white rhino or something like that . It's their high vel birdshot. I don't think it was the gun's fault on this end. It seemed the hulls were expanding too much and getting stuck in the gun and the ejector couldn't strip em out .

Could have just been that run of shells, but it didn't inspire confidence .

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...