Genesis Arms Gen-12 12 Gauge Upper for AR-10 Lowers – Video Review

Genesis Arms Gen-12 by Graham Baates of GBGuns
Genesis Arms Gen-12 by Graham Baates of GBGuns

U.S.A.-( Chances are unless you’re an avid AmmoLand reader you’ve never heard of Genesis Arms.  A small and innovative company based out of Kellog, Idaho, Genesis Arms has found a way to make a 12-gauge upper and magazine that works with an AR-10 lower.  The Gen-12 is not simply another AR-looking shotgun, it’s an upper that slaps onto your AR-10 lower and runs.  The bolt catch and magazine release need to be changed in your lower to function ideally, but no functionality is lost with your standard .308 upper.

Take a closer look at the way they made this work in the tabletop video below:

Short-recoiling systems like the one employed by Genesis Arms can have some sensitivity to the weight that is reciprocating.  That is to say the weight of the barrel plays a role in how well the gun will cycle given the recoil energy of any particular load.  For this reason we opted to do our first range test without any muzzle devices that would add to the weight.  A muzzle brake could further complicate things when the brake’s baffles pull the barrel in the opposite direction.  Since a malfunction of any sort with a muzzle device attached would likely be more the fault of the muzzle device than the gun or load we thought it best to first test without one.  We needed to establish a baseline of reliability first and so hit the range with ten different loads ranging from slugs to birdshot, high-brass and low.

To see how the Gen-12 ran, see the Shooting Impressions video below:

As you can see, even with the light-weight and new-to-shooting Maddy behind the trigger the Gen-12 managed to run everything we threw at it.  As she noted, and part of the value of having non-professionals experience new guns, the AR-format controls made this rather exotic firearm easy and familiar to operate.  So are there any drawbacks?  That could depend on your wallet.

The Gen-12 is not a simple clone of another gun, nor is it an import made inexpensively overseas.  This is a unique system that has required a lot of American engineering and American labor to produce.  As a result the Gen-12 in both shotgun and firearm variant list for $2,230 at the time of writing this article.  Aside from the performance you’ve seen what else does that buy you?  Specifications are listed below as taken directly from the Genesis Arms website.

  • 7075 T6 billet aluminum receivers and hand guard
  • Type III Hard Anodized
  • Continuous MIL-1913 top accessory rail
  • Right side charging handle
    18.25″ (Shotgun length) 4140 chrome molly steel barrel finished in black oxide
  • Chambered 12ga 2 3/4″ and 3″
  • 5 round polymer magazine
  • Magpul CTR buttstock or SBA3 Collapsable Brace
  • Handguard accepts Magpul MLOK attachments
  • Padded case, owner’s manual, and warranty card
@Maddy_A.R of GBGuns with the Genesis Arms Gen 12

Perhaps what impressed me most with the Genesis Arms Gen-12 was their ability to create a magazine for a rimmed, 12-gauge cartridge that can fit inside the magazine well of an AR-10 and still provide proper feed geometry to actually work.  Looking back through firearms history we don’t always recognize revolutionary changes in firearms design.  Contributing steps in what is feasible aren’t always the ones that gather the most attention until they have already become the norm.  I believe Genesis Arms has made one of those steps, and with the Gen-12 “firearm” falling nicely between the NFA guidelines this is certainly a gun to get ahold of while you can.

About Graham BaatesG B Guns

“Graham Baates” is a pen name used by a 15-year active Army veteran who spent most of his time in the tactical side of the Intelligence community including tours in Afghanistan and Iraq. Post-Army Graham spent some time in the local 3-Gun circuit before becoming a full-time NRA Certified defensive handgun instructor and now works as an industry writer while curating a YouTube channel on the side. Visit Graham on Youtube .

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Cool idea but yes the cost is very hard to swallow. I do have to say I did think the magazines where going to cost more the $22. I’ll stick with the F12 Typhoon.

Michael Constenius

I love the idea but that price tag is going to make it mighty hard to sell guys.


I’m sorry guys but there is no way I’m paying that much $ for a hodge-podge AR-10 12 gauge firearm that might be finicky 2 the muzzle attachment. On the other hand the ingenuity is original and might lead to other interesting innovation but if I’m going to pay that much cash for a shotty I’LL get a Benelli M4 or just stick with my Vepr 12-01 that I love BTW

Stuart B Percell

Nor is anyone else.


Why bother changing your A10 over. A shotgun isn’t all that expensive if you want or need both. Seems like a lot of wasted time to me.


$1,550.00 for the Gen 12 upper, Are you frigging CRAZY ? You can buy the complete DPMS .308 for $1,300.00. Gotta be at LEAST a 200% to just under 300% markup on the Gen 12 upper, I’ll pass. The high price will keep sales very low.


I just sold a NIB DPMS AR10 for under $700. Depending on model, $1300 is WAY too much.


Absolutely will never be for me but hey, it’s a gun or, at least the upper for one, so it can’t be bad and I’m sure somebody will love it. If they don’t these will become so rare that in 20 years, long after I’m gone, they’ll bring in very high prices as collectors items. Even higher than they already are!