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Posted: 9/27/2015 8:25:36 PM EDT

An old man friend of mine bought a Mossberg 930 and it's been a jam-o-matic since the day he bought it.  He said he's only put about 10rds of 3" high velocity ammo through it (that's what the gun store told him to use) and it's jammed since day one.  I took it out today and tried everything from el cheapo dove load to good 3" stuff and never got more than 5 rounds to cycle without the type of jam seen below.  He seems to think the lifter is hanging lower than when he first bought it, but from all the pictures I can find online, it looks normal to me.  Any tips would be greatly appreciated


typical jam





Link Posted: 9/27/2015 9:40:54 PM EDT
[#1]
Figure it out, because I want one.
Link Posted: 9/27/2015 9:45:48 PM EDT
[#2]
Did you disassemble it and clean it well before shooting?  Mine shoots just about everything including the cheap Walmart Winchester target loads that most say won't cycle.  Can't tell a lot  from the pics but there looks to be a rail added to the top of the receiver.  Some of these rails come with screws that are too long which may be something to check.
Link Posted: 9/27/2015 10:01:13 PM EDT
[#3]
Pm GunCat and get him to jump in here.  He knows his stuff.

I am not a Mossberg semi auto fan, and have seen this in guns shot by occasional shooters at the gun club.

Outside of the the obvious (everything clean, nothing impeding feeding in the receiver, no burrs or crap on the chamber ramp or bolt face), I don't have any suggestions outside of what you have tried.

Link Posted: 9/27/2015 11:33:07 PM EDT
[#4]
I can't tell from that pic what the front of the shell is stopping on. What is it stopping on? Does it always stop against that same place?
Link Posted: 9/27/2015 11:58:46 PM EDT
[#5]

I didn't clean or disassemble anything before shooting.  Since posting, I found out the old dude only fired about 10rds and gave up.  I ran through about 30rds today.  I'll take it apart, clean, lube and report back.


As for where it's catching, the bottom of the shell is catching just the bottom lip of the chamber.  Same spot every time.  It's almost like the shell isn't quite lifting up high enough or the bolt isn't coming forward with enough force.  I can manually rack the bolt when it hang up and the round goes in.





Link Posted: 9/28/2015 12:15:01 AM EDT
[#6]

The reliability on mine vastly improved since I started cleaning it properly.

No lube in the gas piston.

Link Posted: 9/28/2015 12:19:49 AM EDT
[#7]
Yeah, see what's happening after clean & lube, but if still the same problem then the carrier or dog will need to be changed so it lifts a little higher. I'd send it back to Mossberg if it's new or new-ish and make them fix it. Probably just all that factory preservative lube causing it currently.
Link Posted: 9/28/2015 6:43:04 AM EDT
[#8]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I didn't clean or disassemble anything before shooting.  Since posting, I found out the old dude only fired about 10rds and gave up.  I ran through about 30rds today.  I'll take it apart, clean, lube and report back.


As for where it's catching, the bottom of the shell is catching just the bottom lip of the chamber.  Same spot every time.  It's almost like the shell isn't quite lifting up high enough or the bolt isn't coming forward with enough force.  I can manually rack the bolt when it hang up and the round goes in.

View Quote


The mag tube, gas piston parts and barrel ring need to stay clean. The 930 needs attention after it is shot. It is not a gun that you can routinely run a few boxes of shells through then put it away for a month and expect it to run next time you need it.

Keep the outside of the magtube clean. Keep the gas piston clean and make sure all 3 parts of the piston are clean enough to move around and rattle when you shake the piston (when carbon builds up the snap rings on the piston expand and hang the piston in the barrel ring tube).

Check for a sharp edge where the extractor slides in the barrel/chamber area. Slightly round off that sharp edge.
Link Posted: 9/28/2015 7:59:52 AM EDT
[#9]
I have three of them. I bought all three used for a song from guys that " COULDN'T MAKE THE DAMN THINGS RUN" for a song.

All three had plugged up gas ports. One of them I pulled a pencil eraser sized blob of crud out of the gas ports. Clean the gas ports well, really well
Link Posted: 9/28/2015 8:42:35 AM EDT
[#10]
Also, pick up a pack of Wolff extra power mag tube springs, and chamfer the mag tube and extension so the follower doesn't hang up.

As for the issue in the OP, Haven't seen one quite like that. The lifter may indeed be sitting a little low, which would be an easy fix for someone with a TIG that knew what they were doing.

When it hangs up like that, can you push up on the lifter a bit and have it drop into battery?

BTW, stay away from any of the Winchester SuperSpeed, SuperTrap and Universal crap, that stuff is junk in semi-autos.

Link Posted: 10/6/2015 2:24:15 AM EDT
[#11]
Not sure why yours jams so much. Mine ran great and I never cleaned it. I put about 2k rounds through mine before it started jamming. I cleaned and lubed it and it ran great again. And all I run is cheap walmart federal 2.75 #7 1/2 shells.
Link Posted: 10/9/2015 6:07:05 PM EDT
[#12]
So, unless its spotless clean, and oiled EXACTLY right, its not reliable?


K. But at least you saved $ by not getting a Benelli.  
Link Posted: 10/9/2015 6:22:31 PM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
So, unless its spotless clean, and oiled EXACTLY right, its not reliable?

K. But at least you saved $ by not getting a Benelli.  
View Quote


That has not been the case with mine over a few thousand rounds...
Link Posted: 10/10/2015 12:16:05 AM EDT
[#14]
I plan on stripping it down this weekend.  I'll report back
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