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Mossberg 935 shooting 2 3/4"

I have tried shooting high brass 2 3/4" shells and various low brass loads as well, neither will eject! It's not a brand new gun, been shot plenty of times with 3" duck loads, so I don't think it's still in the "breaking in" phase that most people cite on this issue.

Is there anything I can do to the gun to make it eject 2 3/4" ? Some suggest an o-ring might work. I would really like to be able to at least shoot high brass 2 3/4" shells out of this gun for dove hunting. Is there anything that anyone might be able to suggest to help? Thanks
Been reading about the OR3GUN marine spacer tube to address this issue...really thinking about ordering one to try it. Does it work as advertised?


Elite Member
I believe the barrel on mine says it will only handle 3" and 3.5" only? Not for sure though. If it will reliably shoot 2 3/4" or we can make it do it, that would be great. I want to take some trap and skeet lessons someday and I want to use my 935.
It will shoot 2 3/4 just fine, the problem is it won't eject them, so it's basically a single shot at that point. The marine spacer tube on their website says it is made for the 930/935 series shotguns, I am just wanting a little reassurance that it will work as advertised before I order it, maybe hear from a person or two that they have used it on their 935 and it ejects low powered shells now.

I'll probably end up ordering it either way, I really want to get it shooting these field loads.

Perhaps it's their "competition spring plunger" that I need to get this gun cycling lighter loads. Would really like @OR3GUN to chime in on this!
I emailed William Reeves through the OR3GUN website, and he advised me that I should try the competition spring plunger in order to get the 935 to cycle light loads. Ordered today and will update whenever I get it installed and test it out.


.270 WIN
Had mine out about three weeks ago with some friends. Had picked up a box of 2 3/4s as well as some 3 and 3 1/2 that I already had. Handled everything fine but the kick is there in the 3 1/2s if you keep shooting clays. Could shoot the 2 3/4 all day. Others used it too with assorted ammo with no issues.
Well, I received the OR3GUN CSP (Competition Spring Plunger) in the mail today and replaced it. Unfortunately it performed the same as before, not cycling 2 3/4" shells.

Honestly, when I received the part, I was sort of disappointed. It didn't look like it could change anything, it just looked a little different than the original. So before ever replacing the part, I kinda had my doubts about it actually working as advertised, and unfortunately I was right. Now I am feeling like I wasted $30...

Disappointed to say the least :(


For some reason we aren't getting email notifications from the forum lately. I'll need to dig into our settings and see what's up.

Luke, there is something else going on with your 935 that we'll try to walk you through finding here. Our in-house 935 with the shortest available barrel (22") will now run 1200 FPS 2 & 3/4 bulk packs flawlessly and there is no reason yours shouldn't with the right parts and maintenance issues addressed.

Here are a few things to check on your gun to make sure that you are getting full gas to cycle light loads.

1) Remove your forearm and disassemble the gas system. Does your piston slide smoothly in the cylinder? Does the piston slide smoothly over your magazine tube? Once re-assembled, does the piston still slide smoothly as an assembly? Does the mere weight of the spring behind the pusher return the piston fully forward or does it bind? If it binds, your piston may have been welded to the barrel at a slight angle or your rings are packed with crud and need to be removed from the piston and cleaned separately. The rings are easiest to address. Also, run your gas system DRY, without lube and see what happens. Since you don't have a Marine Spacer Tube, keeping lube off of your gas system is critical. This is also the time to check for rust pitting, gouges or scoring on your magazine tube and check that your secondary gas system's ring is intact. If your secondary gas system or magazine tube under it is scored up or pitted, this is where all of your gas is escaping. Escaped gas in this area isn't available to help cycle the gun. Also, some 935s quickly develop cracked pusher assemblies and/or forearm retainers. If either of these polymer items are cracked or broken, they can create drag on the pusher assembly where it meets the receiver or potentially contacts the forearm.

2) What was the condition of your factory plunger when you removed it? Chattering on the plunger from a spring burr? If you have a spring burr you likely also have a scored recoil spring tube. It is important to remember that the 935 uses the same spring as the 930, but has to compress it another 3/4" and naturally runs a higher spring weight than a 930 as a result. There is also additional weight to the bolt and slide assembly working against it. If your recoil system is providing drag, it is an uphill battle. The CSP drops the peak spring weight of the 930/935, but it won't drop the 935 below the weight of a standard 930. Some 930s have issues running 1200 FPS loads reliably. The recoil system has to be running right to cycle 1200 FPS 2.75" shells in a 935.

3) Other things that are common culprits in 930/935 cycling issues include side saddle shell holders that attach through the trigger group pin holes. The receiver to trigger group fit is designed to be loosely fit in the 930/935. Cinching a side saddle down on the receiver will narrow the rails in the receiver and slow or bind the cycling of the gun up. Another possibility is that your barrel needs a good polishing. If an empty shell is tough to extract, the marginal amount of gas available to cycle a 935 with 2.75" shells is spend dragging a sticky shell out.

As stated in our recent email, specifics on the load you are trying to cycle and answers to the above check list will go a long way to figuring out why your specific 935 won't cycle light loads.



When I inspected the magazine tube, I do notice a couple small spots with a little bit of pitting. Do you think that is causing my problems? If so, is there any solution to that?
think im just gonna sell or trade this shotgun..i've pretty much given up on getting it to cycle 2 3/4" shells. Thanks for the excellent customer service William and good luck in your endeavors!


I wouldn't give up on it just yet. A new magazine tube from Mossberg is around $25, maybe $35 if you can get the Boron Nitrided one for the JM Pro series. These won't rust and you'll have a new, non pitted surface for the gas system to live on. This is a common path of degradation for the blued tubes on the 930/935. Once the tube is scored or pitted, trying to fix it with steel wool or sanding it out just makes it seal worse. Our Marine Spacer Tube helps keep the blued magazine tube from rusting, but once the pitting is there it won't be much help. Give Mossberg a call. The part number for the JM Pro magazine tube is 5861BN. If you wanted to ensure you were putting the corrosion issue behind you, the JM Pro Piston Assembly is 16801BN. The 'BN' in each part number is critical as these are the Boron Nitride versions. I could get you a new blued magazine tube as I have one in stock, but would highly recommend getting the JM Pro version.

Buddy S

Copper BB
Did they hook you up LukeShutes? I've had inconsistent luck with asking for parts.

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According to his profile...Luke was last seen on this forum 9/29/15...posting above.