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Look closely at the receiver which that FLEX buttstock is (mostly) attached to. That’s not your grandfather’s Mossberg 500: it’s an MVP bolt-action rifle in .308 Winchester. It also takes M-14 mags (which is awesome BTW) but it’s not the only Mossberg model that’s getting the FLEX treatment . . .

Mossberg floated their FLEX modular hardware system about two years ago, and I have to confess that I was initially skeptical. I didn’t think any quick-detach stock mounting system would ever stand up to 12-gauge shotgun recoil without wobbling and creaking and, well, flexing until it drove me mad. After several hundred rounds of testing, I had to conclude that I was I wrong.


Way wrong; the FLEX stock setup has been solid as a rock. TTAG’s readers seemed to agree with my conclusion, and chose the 500 FLEX as the Reader’s Choice Shotgun Of The Year. Mossberg has been paying attention to the success of the FLEX system, and now they’re FLEXing just about everything in their catalog.

The ‘Just In Case’ Model 500 comes in an airtight, buryable PVC pipe just like it always did, but its ‘cruiser’ style pistol grip is now FLEXworthy. You can stuff a standard FLEX buttstock into the PVC storage pipe along with the pistol grip and change the gun’s entire philosophy of use.

The FLEX system offers so many buttstock lengths and options that it’s an obvious choice for setting up smaller shooters. Our 12-gauge FLEX 500 test gun was easily configured to a weight and pull length that made it fit my petite teenage daughter, but as a responsible parent there was no way I was going to let an 80-pound shooter touch off a lightweight 12-gauge shotgun. If I’d had a 20-gauge FLEX, we would have been out busting clays months ago.

Mossberg read my mind, and the first new FLEX shotgun they showed us was the Model 500 in 20 gauge. It uses the same standard FLEX buttstocks and fore-ends as the 12-gauge version, and the same barrels as any 20-gauge Model 500. It’s a great choice for smaller-statured women as well as for young shooters, because the gun can grow with them. If your young son grows and wants to move up to a 12-gauge, you can buy a 12-gauge FLEX and use your existing stock and fore-end.

Most of Mossberg’s MVP lineup of bolt-action centerfires has been FLEXed as well, including the .308 version shown here. Joe tested the 5.56mm MVP Predator about a year ago, and has since used it to send innumerable Oregon ground squirrels and coyotes to the Great High Desert In The Sky. Both Predator and Varmint 5.56 and 7.62 MVPs are offered with the FLEX treatment, although obviously you won’t need any FLEX fore-ends for them. The one MVP that can’t use FLEX buttstocks is the military/police oriented MVP Patrol.

Light-kicking 20 gauge FLEXes were a no-brainer and centerfire bolt-action FLEXes were a pleasant surprise. Mossberg’s Linda Powell really blew us away, however, with the final FLEX surpise: this .22 FLEX 702 semi-automatic.

The FLEX buttstock makes this the perfect choice for young shooters, and it also turns this (let’s face it) pedestrian .22 autoloader into a totally bitchin’ takedown rifle for camping or truck-gun duty. The 702 FLEX was kept under such tight wraps that even Mo own Director Of Media Relations only learned about it here at the show. The Ruger 10/.22 Takedown and Marlin Papoose have just got some competition. Unlike those two takedown .22s, you can still fire the Mossberg 702 Flex when it’s broken down if you have to.

Most of the guns in the Mossberg catalog are now available as FLEX models, and I say this is a bloody good thing. Nearly any Model 500 can now be a convertible, scaleable takedown shotgun, and almost every MVP rifle offers similar portability and versatility.

What didn’t Mossberg FLEX? It’s actually kind of a short list. You can’t FLEX an AR-platform rifle because of the buffer tube (AR’s are modular enough already) and you also can’t FLEX the Model 930 because the autoloading shotgun’s recoil spring rides within the wrist and buttstock. Basically everything else in the catalog, with only a few exceptions, will be takedown guns that can switch buttstocks across calibers and model numbers.

Veni, vidi, FLEXii?

We’ll see.

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  1. Just curious, but how does it work with going from a shotgun with a stock, to one with only a pistol grip (or vice versa) with the FLEX system? That doesn’t cause legal issues or the need to register?

    I guess it’s not the same as putting a stock on a ar-15 pistol?

    • As long as the barrel and the assembled shotgun meet the minimum legal length, the feds don’t care what the buttstock (or lack of it) looks like. Pistol grip-only shotguns don’t work too well for me, though, which is why it’s so much more useful to stick a real stock in that Just In Case tube.

      ‘Just in case’ you really want to hit what you’re aiming at.

    • No its not similar to an AR-15 pistol with a stock. You forgot about Barrel length. Shotguns have a minimum barrel length of 18 inches. Because the barrel length remained 18 inches even though the user put a shoulder stock or a pistol grip on the shotgun it’s still a shotgun. No paperwork required. The only thing you have to worry about with a shotgun is trying to put a barrel shorter then 18 inches on. If you have a shotgun with a barrel less then 18 inches it is an Any Other Weapon regardless of the stock setup, and requires registration. But thats the only case.

      • don’t forget overall gun length. usually not a problem unless you decide to pistol grip an 18″ break open shotgun.

      • Not quite right. A shotgun with a stock and a barrel less than 18″ is classed as a Short Barrel Shotgun, which is a $200 tax stamp. A pistol grip shotgun that leaves the factory that way and had never had a full stock on it turns into a AOW when you chop it down, that’s a $5 tax stamp.

  2. Why not make all the barrels 20″ long and have choke tubes be external with internal thread that happen to be 4″-8″ long? Then you could have the same gun be home defense, turkey and upland bird/water fowl.

    • Because, people already do use one receiver to do 2 jobs, by changing barrels.

      Why reinvent the wheel?

  3. I like the FLEX concept. But, I really interested in the .308 MVP that takes M14 magazines. Does a threaded barrel come with it too? Please post more information on it.

    • That sounds good for people with M1A’s or Armalite AR10’s, but I’m confused. About a month or two ago, a couple of websites broke the news about the MVP 308 and said it accepted SR-25 style mags. I also talked to a Mossberg rep who said the same thing. So, was that a lie or did they figure out a way to allow it to accept both SR-25 AND M14 mags? I agree, more info is needed!

  4. Because having multiple barrels for one gun is expensive. Extra long choke tubes can be made cheaper and therefore bought cheaper. They could be added/removed by simply threading.

    • But what you and I consider expensive barrels, Mossberg considers revenue. Besides multiple barrels are cheaper then multiple guns. And I suppose there is probably a gas pressure or durability issue that makes a continuos barrel of the desired length advantageous over extra long chokes.

  5. Did you mean the .308 uses pmags? You said m14. Did they have one with sights and a threaded barrel? That is what I want. Something like the gunsight scout.

    • I heard the same about the MVP 308 accepting SR-25/Pmag style magazines, as well. That’s the main reason I wanted it over the Ruger Scout with its expensive Accuracy International mags that only come in 5 and 10 rounders. Here’s hoping they found a way for it to accept both M14 mags and SR-25/Pmags.

  6. The MVP in 308 looks nice, but a little to expensive. Can Savage please make a 20 round magazine fed bolt gun. Hog hunter that takes PMAGS

  7. I can already envision a FLEX variant for tubed stocks. The Mossberg FLEX uses a T-shaped spring-loaded locking mechanism whose rotational axis is on a pin that goes down through the center of the connector. That’s great because it allows a solid lock-up while allowing a simple push-on installation for the stock, as the connector provides the anti-rotation and the locking mechanism provides the friction preventing the stock from sliding off. if, however, there was a rotating lockup (similar to a bolt head) the locking mechanism would only have to provide anti-rotational force as the lugs/threads of the rotating connector would provide the anti-sliding friction. (I’m not a physicist, so forgive me any incorrect terminology.) The pin, no longer needing to run through the center of the connector, could be moved to the side. It might add a bit of height and width to the mechanism, but would allow a spring and buffer to run through the middle of the unit without obstruction.

    ETA: A stock which has a sufficiently-sized cavity to house a buffer tube could then be used with this type of connector. I’m really not sure what the advantage would be having such a mechanism on an AR platform since it’s already easy to replace a stock on a carbine buffer tube, but other buffer-tube equipped firearms (like auto-loading shotguns) might benefit from this.

    ETA: I take that back. I know exactly how this could be used with an AR … But I’ll let your imaginations run wild with how.

  8. I wonder if they’ve given the flex treatment to their leverguns. They’ve already got a Frankenlever with an AR-style stock and quad rails (fascinating and repellent at the same time), so this might be the next inevitable phase. Lever-actions are the original assault rifles, after all…

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