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New JM Pro 22” - Here we go!

Good day everyone! Thank you to the admins as I am new to this site. Thought I would share my findings & mods with everyone here for current members and future ones too.

First off, I’m happy as a clam. Just brought home a new Mossberg 930 JM Pro 22”. Local shop added some lube, and put 150 rounds of Remington Small game load #6/1oz thought it to break it in, before I brought it home for its first cleaning.

Jerry Miculek has a great video to follow:


During this process I thought it would be good to test and show how dirty the piston and tube spacer can get and if an aftermarket piston and tube spacer could improve on this.

I will post my finding here and keep it updated as I go along. Mind you, I travel for work so I won’t be always testing...but when I am home let the fun begin.

Here are pics of what my piston and tube spacer looked after first disassembly:

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Cleaned everything up and gave some things a polish for a perfect start:

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Cut out some grip tape:

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And done. Notice tape on stock grip, and Nordic rail:

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Things to come:

A SBE Precision Follower and End Cap extension are on their way. Going to get the piston after I put this stock one through some paces.

Holding off on the Or3Gun stuff for a little too. Really want to see how this performs.

New lifter on the way from Mossberg and sending that off to C-Rums or may check out a coupe shops here locally...want to get the loading port opened up more.

Well thanks for looking and looking forward to the results. May take some time but patience is a virtue.



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Looking good. Keep the updates coming Sinewavz!!
Thanks Jmm. Will do.

Just ordered the Multi-use MST w/ Teflon, the CFR Anodized for twin/quad loading, EBR Tactile, and the sight Saddle optic from Or3Gun. Not going to install the MTS till I put the stock one thru some paces, then swap, and then make my own mods to the stock and see how they all compare.

Also ordered the HiViz TS1002 to see if I can use it as a rear for now. Ideally, I would like to keep the front bead sight for clays, and swap to a RDS on the side saddle for Open Comp. So stock bead with HiViz rear for tactical class, then swap it out to the saddle w a Venom or Burris RDS on it for Open class.

Right now, I’ve been searching around to find someone locally (San Diego, CA) to open my loading port more...hence the CFR from Or3Gun. Wanted to get that part before I did the loading port mod so it will be fitted perfectly.

Finally, sending out my Lifter for welding later this coming week to C-Rum unless I find anyone (again locally).

Really, the reason I am doing this is because I could not google enough info on mods, and what the outcome was for each mod to the JM Pro. Little bits here and there but not enough. So for those that own, or are looking into a JM Pro, please feel free to post here.




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Last edited:
Other updates you may think about ...
You will need to update the bolt release pivot pin - it will break
I also radiused the shell lock lever to feed more reliably


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Other updates you may think about ...
You will need to update the bolt release pivot pin - it will break
I also radiused the shell lock lever to feed more reliably


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Have any pics of your shell lock lever mod? Love to see it.


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Had a little time to test and adjust a couple things lately. Received a bunch of things and wanted to throw them in but I held back....one thing at a time.

Installed the SBE extended end cap (+1) with the stock follower. Loaded it up (dummy rounds) to check capacity/spring issues and zero issues. Now I’m rolling 9+1. Good add.

Was going to wait on the SBE follower, but I ran into a double feed during dummy round reload practice. The stock follower was catching on the bolt release, also causing the bolt release to angle.

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This was fixed when I swapped out the stock follower for the SBE one. There was an obvious size difference but it fit beautifully and still 9+1.

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Now that the bolt release button was straight, I could add the Or3gun tactile one. Fit perfectly, and easy to install. One screw and they provide the hex tool with it. Perfect! Another good add.

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Oh yeah...and swapped the Forearm retainer out with the Or3gun double/quad anodized one. The stock one, as most people know is terrible...not snug at ALL. It was the first thing I noticed when I held the 930 for the first time. Mossberg should have built it right in the beginning or at least have fixed it by now.

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Also received the extra carrier/lifter from Mossberg and sent it off to C-Rums. Got there yesterday and Jeff said a week turnaround so till then I’ve smoothed out the stock lifter as much as possible without changing it. Want to keep it JIC.










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I’m liking what you’re doing here. I just got my 22” JM Pro last weekend. Quickie field test cycled all brands of $5/box Walmart ammo (5 rds. ea.), smashed all but 1 hand-thrown clay, then I head off to plug a few dove on opening day. About 150 rounds through it so far with only one malfunction from a Winchester cheap round where the rim of the shell failed at the extractor and the shell failed to eject. Upon further inspection of like empties, several other Winchesters were deformed on the rim at the extractor hookup too.

Anyways, my thumb nail has already been bitten by the lifter far too many times and the forend rattle is equally annoying. My factory MST has a burr on it already (may have been there before I shot it - who knows), but the gun is cycling low brass plenty fine. So, OR3GUN Multi Teflon MST and quad CFR ordered, SBE piston and follower ordered because it seems like the right thing to do, and that leaves the lifter, sights, and stock to address.

I bought this one NIB on the used market from a gent in Tulsa (if you’re on here, thanks again!), and it didn’t include the stock shim kit. Figured I’d try the factory parts before more OR3GUN stuff, so got that kit ordered ($25 from OFM) along with the giblets to run a stock length mag tube so my more cultured acquaintances don’t look at me quite as funny on the trap range.

Haven’t found any references to C-Rums yet, just SKY Tac for the lifter, so I’ll look into that.

Speaking of funny looks though, I’m really leaning hard toward the Leupold Deltapoint Pro on a Kengs mount for sights. I ran a Saiga 12 with a Primary Arms micro dot years ago and loved the setup. Not the sight itself so much as the sight picture. That decision will have to wait a few weeks, but we’re thinking a lot alike - thanks for sharing!

Edit: can you post a pic of the SBE mag extension installed too? My local shooting range went out of business last week, and choke tubes were 50% off. So, I bought an almost full set of extended Carlson choke tubes for the Mossy family. The extension ought to be about flush with an extended choke tube...
 
Hey Abyss! Sounds like you’ve got a good project going too. I haven’t updated this post in a sec just because I have been crazy busy. I’ll be sure to update it when I get back from this tour.

Here are pics of the SBE Nordic +1. My buddy gave me his Carlson breach choke so here it is for comparison on length.

Also C-Rums did a bang up job on my lifter. Good stuff. No more thumb challenges. Personally, I opted to ordered another one from Mossy, then sent that to C-Rums and it was back in my hands within a week from when it was received.

Next up is doing some work on the loading port....still haven’t touched it....yet.

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Hey Abyss! Sounds like you’ve got a good project going too. I haven’t updated this post in a sec just because I have been crazy busy. I’ll be sure to update it when I get back from this tour.

Here are pics of the SBE Nordic +1. My buddy gave me his Carlson breach choke so here it is for comparison on length.

Also C-Rums did a bang up job on my lifter. Good stuff. No more thumb challenges. Personally, I opted to ordered another one from Mossy, then sent that to C-Rums and it was back in my hands within a week from when it was received.

Next up is doing some work on the loading port....still haven’t touched it....yet.

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What length barrel is that?
 
Not to be a master of the obvious or a flagrant smarta$$, but the thread is titled, "New JM Pro 22” - Here we go!"

Oops! I should have caught that. Was perusing the forum and ran across his pic of the Mag extension cap, which appeared to be on a shorter bbl. My apologies.
 
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