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my new JM 930 is a jam-o-matic

X

xLucidx

.22LR
I bought a mossberg JM 930 a couple weeks ago to shoot some 3 gun

the day after I bought it I ran about 50 rounds of birdshot 25 federal and 25 fiochhi

had maybe 1 jam with the federal and a few with the other, I figured the gun just needed broken in.
Then I went to slugs and noticed my POI was pretty far left.
I'm not new to shotguns and I know my sight picture was correct, plus the rib on the barrel was canted with the receiver. So I shot an email to Joe at mossberg who seems the be taking care of everyone.

he sent me a new barrel fedex 2 day and corrected the cant. All should be well.
now the gun is just a Jam-o-matic

wont run with anything for more than a shot without jamming. So I put the old barrel back on thinking the new one may need fitted.
Well it jams exactly the same with the old barrel as well.

so now Im at a loss.
It seems as though the elevator drops just a hair to quickly as the bolt is slamming home causing the shell to jam halfway in the chamber.
I sent Joe another email and made a youtube video



anyone else have anything like this happen?
I know the first runs have had problems, but on the box my gun was packaged and sent to an FFL in December of 2016

ive cleaned the gun a couple times per the Jerry miculek video and it seems smooth as butter. it just jams
 
I have not had a problem with mine purchased in '12. Does it feed normally from the mag tube or does it jam as in your video? Lotsa help on this site so someone more knowledgeable than me should be along to help you out.
 
still jams regardless of feeding from the tube or dropping a round in the action.

Yesterday I loaded the tube up and dropped one in the chamber letting the bolt close on it just to see if the gun would run.
Jammed on all 9 shots. I could shove the bolt the rest of the way closed with some force.

I gave up on it as I was getting annoyed and about to throw it in the creek :\
 
If those little set screws on top of the receiver stick down only a couple of threads beyond flush on the inside of the receiver, it can cause what looks exactly like the kind of jams in your video.

The two in the front can deflect the barrel extension down to the point that the bolt can hit it on the way forward.
 
Can you disassemble the gun as show what the top of the bolt looks like?

With the trigger group removed, can you take a picture of the otherwise assembled gun from the bottom?

Any indications (on the rounds you attempted to chamber) of contact/hanging on the chamber?

Another useful picture would be of the forearm removed and your gas system assembled onto the gun.

Don't give up on it yet. It has to be something simple that may be hard to diagnose over the Internet.

Thanks!

William

http://www.OR3GUN.com
 
OR3GUN said:
Can you disassemble the gun as show what the top of the bolt looks like?

With the trigger group removed, can you take a picture of the otherwise assembled gun from the bottom?

Any indications (on the rounds you attempted to chamber) of contact/hanging on the chamber?

Another useful picture would be of the forearm removed and your gas system assembled onto the gun.

Don't give up on it yet. It has to be something simple that may be hard to diagnose over the Internet.

Thanks!

William

http://www.OR3GUN.com
Click to expand...


Here are the pics you requested sir.
I also backed the scope mount screws out a couple turns just to be sure, I dont think they were touching the barrel. Maybe the front one just a hair.

bolt


bottom view


gas system


trigger group


receiver with the bolt removed


the rounds dont have anything abnormal looking on them
obviously a few scuffs from when they jam but thats it.

I noticed the trigger pins have one groove on one side with 3 grooves on the opposite side, they dont look directional to me though?
 
That looks like a lot of bolt and internal receiver wear for so few rounds through a new gun. We have in-house guns with thousands of rounds that don't have that much wear on the top/front of the bolt. It almost looks like it is being pushed up as well as forward in your video. I'm guessing your barrel cant may have also affected your lockup.

Does your locking lug move freely within your bolt? How does the bottom of the bolt and top of the slide (bolt carrier) look. Does your link (attached to the rear of the slide) move up and down freely without much side to side travel?

Considering the initial issue you had with the gun, I would get it back to Mossberg to take a detailed look at unless you have a second 930 handy to swap and compare parts in order to find where the tolerance is off.

William

http://www.OR3GUN.com
 
yea i was thinking the same thing myself.

it has a total of maybe 60 rounds through it.
a few times when it jammed I pushed the bolt the rest of the way home - could cause some of the extra wear.
the carrier looks good with minimal wear. obviously a little where it slides in the receiver but nothing unusual looking.

locking lug moves freely without problem as well as the link.
It does not look to me like there is any excessive play with the link, but this is my first 930.

I messaged mossberg on facebook yesterday and got a prepaid fedex label for it to go back.
I think in my letter included in the box I will add a note about excessive wear on the bolt.
 
xLucidx said:
a few times when it jammed I pushed the bolt the rest of the way home - could cause some of the extra wear.

I messaged mossberg on facebook yesterday and got a prepaid fedex label for it to go back.
Click to expand...

I wouldn't think the extra wear was from just pushing the bolt closed with your finger/hand.

Wear is understandable and even expected with a gun with a lot of rounds through it, but that seems like a lot on a new gun with less than a few boxes of shells through it. I don't think it's anything you did.

The wear on top of the bolt and the top of the receiver is the area I am referring to.

But without the gun in hand, I'm only speculating and I've been known to be wrong before.

Glad you got a shipping label. Last time I emailed them about a part, they wanted me to ship the whole gun back to them and pay round trip shipping for a $2 part.

Needless to say, my safety still doesn't work on my 500.

Sorry that you're having trouble with it. But once they get it lined out, I think you'll be happy with it. I only own one semi 12 gauge. And it's quickly becoming my favorite.
 
From your pics: the barrel extension is being pressed downward, causing the wear on the leading edge of the top of your bolt. I suspect the peening, behind your rearmost receiver mounting screw, is from the rear of the bolt bouncing upward when released from the pressure. Possible causes: forward receiver mounting screws are pressing down on the barrel extension; the barrel is not fully seated, either because of left over milling marks, or just not "wiggled" fully into it's recess.

Edit: Have you removed your barrel? It is difficult to do so?
 
Rob72 said:
From your pics: the barrel extension is being pressed downward, causing the wear on the leading edge of the top of your bolt. I suspect the peening, behind your rearmost receiver mounting screw, is from the rear of the bolt bouncing upward when released from the pressure. Possible causes: forward receiver mounting screws are pressing down on the barrel extension; the barrel is not fully seated, either because of left over milling marks, or just not "wiggled" fully into it's recess.

Edit: Have you removed your barrel? It is difficult to do so?
Click to expand...


yea I have removed the barrel several times, first to replace it with one that has a non canted rib.

I did back the receiver screws out some and I will try that this week before I actually drop it off at fedex.

I also reversed the pins that hold the trigger group in - they dont seem directional but its worth a try.

The lifter does seem like its staying higher a little longer but I havent had a chance to drop any ammo in yet
 
I sent it out fedex on Friday.
Tracking says it should be delivered Wednesday.

Ive still been in contact with Joe Zakher via email, he was going to next day air a lifter to me to see if that fixed it but I chose to just send it in instead of guessing at what parts to try.

Anyone sent anything in recently, what kind of turn around time did you have?
I was quoted 4 weeks by another Mossberg rep.

I figured I would let Joe know when it was delivered in case he personally wanted to take a look at it.
 
Still no word from anyone at mossberg CS, which I hear is pretty much normal as far as warranty work goes.
Seem's communication isnt a real priority.

I did email Joe last Thursday to let him know my gun was delivered on the 29th.
Now im just ancy waiting on it, hoping it comes back working without any signs of being beat up with a quick turn around time.

as many fits as this sucker gave me I miss my shotty!!
 
After Mossberg has had my shotgun for a month now I called corporate HQ to see what the story was.
They had no update for me.

I asked for them to follow up and reach out to the eagle pass facility to get an update, at this point its costing me money due to registering for 3 gun matches earlier this year with non-refundable entry fee's.

I spoke with the product services coordinator (Joe Onofrio) who was going to check with the lead tech at the eagle pass facility (Joe Zakher) and I asked for a call back by the end of business hours today with an update.
 
Well after speaking with both Joe's they expedited my service, my shotgun got back to me on Friday last week.

They replaced the whole bolt assembly as well as the lifter.
I dont want to Jinx myself but it ran about 30 rounds of birdshot and about 20 slugs with no problems this weekend.

Hopefully things are good to go but it will take some more range time for me to build confidence in it.
 
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