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My Home defense Mossberg 930 Shotgun

Discussion in 'Mossberg 930 Autoloader' started by JCinPA, Sep 27, 2020.

  1. JCinPA

    JCinPA .410

    Executive Summary: My standard 930 Field & Security Combo has been modified with

    - XS Big Dot Tritium front shotgun sight

    - OR3GUN CSP & ASR combo

    - OR3GUN MST, multi-purpose, Teflon coated

    - OR3GUN Competition (blue) magazine tube follower (-5% SR)

    - Military style simple sling

    - BrownCoat Tactical shot card

    It has run 100 1-1/8 ounce Winchester and 25 1 ounce Estate target shells through the 28” barrel, and it has run 100 Federal low-recoil 9-pellet 00 Buck, LE 132, through the security barrel without a single malfunction. This was done in one range outing starting with a clean gun, no cleaning or lubrication during firing the 225 shells.

    Long version
    (too long--I'm kinda known for this) if you’re interested …

    So, I’ve always been of the popular persuasion that pump shotguns are THE way to go for defensive use because pumps “always work”. Until recent years, most folks eschewed semi-auto shotguns for defensive use. That was likely driven by the American publics’ inherent trust in anything the military uses, and that was limited to pump shotguns until 1999 when the Marines adopted the M1014 gas-operated Benelli. Now the perception of semi-auto shotguns as defensive tools seems to be changing with the public as well. Maybe it’s been going on for a long time, and I’m just now becoming aware of it, I don’t know, but two things happened that steered me toward a Mossberg 930 for defensive use.

    First, I have a Mossberg 500A field gun with 28” barrel, and because of the current market conditions, I cannot find an 18.5” security barrel for it to save my life. Well, I can, but I’m not paying $250 for one on FleaBay. Second, I became aware that my belief that pump shotguns “always work” is not true. Within days of reading about the occasional elevator issue with Mossberg 500’s a 500C I sold to a friend locked up on him. I have not had it back to try to diagnose it yet, but now I realize while pumps may (on average) be more reliable than semi-autos, they are not magical beasts impervious to malfunctions. I happened to have a 930 “Field & Security” combo sitting around the house, so that solved the unobtainium nature of a security barrel for the 500.

    So I began to read here, voraciously, and watched as many 930 YouTube videos as I could find. I’m impressed the 930 is popular as a 3-Gun competition choice, as well, so I started to think about this logically. What kinds of malfunctions could happen with a gas-operated semi-auto shotgun that would not happen with a pump and why? Well, it could get crudded up badly by high-volume shooting (as in competition-or combat conditions) and it is less likely to run reliably than a pump gun does when crudded up. Cleaning is more critical for a gas gun than a pump. But I’m not going to do high-volume shooting because I do not compete, and never will, and I’m OCD about cleaning. So this is not a huge factor for me.

    Is it a more complex action? Well, yes. Bleeding gas from behind the shell as it travels down the barrel, and that gas operating a short-stroke piston which in turn actuates the bolt is more complex than pulling a pump gun slide to the rear. Likewise, the recoil spring returning the bolt to battery while loading another shell is more complex than running the pump slide forward again. But I began to think that if the gun were clean enough and the recoil system was properly tuned to the loads used, this complexity should not necessarily result in more unreliability. These two things are critical, however—the gas gun must run as cleanly as possible in combat environments so as not to get crudded up, and the recoil system must be both bombproof and correctly tuned to the intended defensive load.

    Most of the modifications with after-market parts for the 930 are aimed at these two issues, although some parts are designed specifically for competition use, like dual or quad speed loading modifications, lightening of the spacer tube to promote faster cycling, enlarging the controls, and other things I don’t care about. Below are the parts I chose and the rationale behind each choice, as well as why I did not choose some mods.

    OR3GUN Competition Spring Plunger and Adjustable Spring Retainer

    Rationale? These guns are commonly not 100% reliable with light target loads with the field barrel, and, although perhaps less often, they are not 100% reliable with low-recoil buckshot with the security barrel. My gun may run like a scalded dog out of the box (many here report theirs does), but the prevalence of light load issues on at least a meaningful percentage of guns logically indicates that the gun’s gas system is right on on the cusp of reliability/unreliability with these loads. I could have just gotten the CSP and had a 10% reduction in spring rate, and that likely would have made my gun 100% reliable. However, I have a less is more philosophy, so I also got the ASR, because I could then go with just a 5% spring rate reduction if that would do the trick. And in the unlikely event a 10% reduction did not do the trick, I could go all the way to -15%. If I end up on the 10% reduction, the ASR money was wasted, but if I can get off the cusp of unreliability at -5% (or if I need the -15%) then it is money well-spent. And I saved a second shipping charge. It turns out the -5% SR reduction did the trick, so I am glad I got it, even if it was not strictly necessary (if -5% worked then surely -10% would have as well), and I could have just gotten the CSP, but I’m glad I have a reliable gun closer to factory spec.



    nitesite likes this.
  2. JCinPA

    JCinPA .410

    part 2 ...

    XS Big Dot tritium front sight

    Rationale? This makes a lot of sense to me, intuitively. I think a red dot on a shotty is overkill, and the XS Big Dot appeals to me more than ghost ring sights. This is my opinion, but I think this product is the perfect sighting system for a defensive shotgun, and bests all other choices. Taking a long shot with a slug is not the gun’s primary purpose, although it can be done. Put your red dots on your carbines, and I prefer the plain brass bead to the ghost rings, for speed of use, but it’s the Big Dot on a defensive shotty for me, every time.

    OR3GUN Marine Spacer Tube, multi-use, Teflon finish

    Rationale? This was likely not necessary for me, as I am not a high volume shooter, and the reduction in spring rate probably got me to where I needed to be. But the more I thought about it, the more I realized the moisture relieving action of this tube was more important than keeping it cleaner in high volume competition, which I absolutely will not get involved in. This one is OEM weight, not the lightweight competition model, again, in keeping with my preference to staying close to original factory spec when possible. Teflon makes it easier to clean, and likely a little slicker, as well. Needed? Probably not, the CSP/ASR likely would have made my gun reliable, but not a waste of money, IMO. As set up now, it is likely well away from the cusp of reliability/unreliability in humid or even pouring rain situations, now.

    OR3GUN Competition Blue Follower

    Rationale?? This was definitely not necessary, the OEM follower works just fine. But, I do like a hi-viz follower, simply to make safety checks easier. Anything reasonably priced that can enhance safe gun operation, I’m a fan of. I just like KNOWING I’m empty when I look at my mag tube.


    Yes. Simple, plain, cheap, two-buckle, military sling. Not needed inside the home, most likely, but good to have if I need to be on patrol, or if I decide to bring it to a neighborhood riot defense situation (although I’d likely have an AR carbine for that). I like slings. I use the Blue Force Vickers CAS on my AR’s, but plain black nylon milspec is fine for my shotty.

    BrownCoat Tactical Shot Card

    I don’t think lack of ammo is quite as big a problem in a defensive shotgun as some folks think it is. For its intended purpose, unless you are in the middle of a riot, five shots of 00-Buck will get the job done. However, having a reload is definitely not a bad thing, but to read the forum here, magazine tube extensions are expensive, a hassle to make work right, make the gun more muzzle-heavy and lots of other things I don’t care for on a defensive shotty. For competition, extension tubes are a great thing, but again, I don’t compete. So, I got the Browncoat Tactical Shot Card sidesaddle, because it puts the extra weight between my hands, and I think the gun balances much better with the stock magazine tube than with a couple more rounds near the muzzle. One shot card. One. If you are in the middle of a riot, you should have brought your AR with extra magazines. If ten 00-Buck doesn’t solve your problem, A) there was some seriously poor planning somewhere along the road leading up to this situation, B) you brought the wrong gun—ooops, and C)it’s just your time. Everyone’s gotta go sometime! :D

    Magazine extension

    No, see above.

    After-market Stainless Piston

    No. They're wonderful devices, to be sure, and coupled with the OR3GUN MST, who knows how long this gun could run between cleanings? But I believe I've hit the reliability level with current parts upgrades, and I'm comfortable without it.

    Tactical bolt charging handle

    I decided against it, it’s bling, IMO, and a waste of money. The factory charging handle is fine, it is about the size of my BCM medium latch charging handle on all my AR’s, and besides, aren’t hunting shotguns ‘tactical’? I mean they need to operate reliably and ergonomics are important to duck hunters, right? The standard charging handle is fine for them. I rack the gun ONCE to get it into action. After that, I will reload before I’m empty and keep feeding, or I’ll lock back, reload, and use the bolt release button, not the charging handle. The stock charging handle is fine, IMO.

    Competition Forearm Retainer

    Nah. I don’t compete, I don’t use dual or quad reloaders, my forearm is nice and tight with no wobble at all. Not needed.

    Extended bolt release

    Again, they may have value for a competitor, but it is a solution in search of a problem on a defensive shotty, IMO. The bolt release button is plenty big, I’ve never fumbled it, and it won’t come into play in a defensive role unless I shoot the gun dry. Hopefully, I can top off the magazine as needed between shots, but if I do shoot it dry, I don’t believe I’ll fumble hitting that bolt release button when needed.

    Aluminum, enhanced safety button

    Nah. Everyone talks about how much more durable the aluminum buttons are, yet I’ve never heard of a standard button breaking. I’m not saying it never has, and if it does, I’ll certainly replace it with an aluminum model. But the OEM button is plenty big for me, and the action is crisp and positive, yet not stiff. It it ain’t broke, don’t fix it.

    So, that’s my 930 defense setup. It’s no better than any other setup, certainly, and I’m not suggesting some of the parts I skipped are not worthwhile. I just tend to like to stay close to operating specs, assuming the designers knew what they were doing, and I don’t like to spend money on unnecessary stuff that could be better spent on shells and training classes. I like her just the way she is right now, she now runs like a scalded dog with anything I want to use, and I feel about as reliably armed as I would with a pump gun, given my environment, shooting training regimen, and cleaning habits. And I like being able to go back to factory SR with the recoil system if I move from low-recoil 00-buck to the regular stuff when I am out of my current stash. I've got a great, tuneable shotty for HD needs.

    Now if I could just find a security barrel for my 500 …
    Last edited: Sep 27, 2020

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