GBGuns may not have done much with shotguns recently, but back in 2018 I discovered a yet little-known company by the name of Genesis Arms. Genesis Arms had created a true 12 gauge conversion for the AR-10 pattern (Gen 1 DPMS pattern). With a Genesis Arms upper, magazine, and beefed up (but still reverse compatible) magazine release and bolt catch one could quickly and easily turn their 308 mid-range gun into a 12 gauge close-range gun.
Through more than a dozen videos and nearly as many articles over the years since then I've kept tabs on Genesis Arms and the seemingly never-ending advances of the Gen-12 platform.
What Is the SSBM? This model integrates a mount system for muzzle accessories previously not possible. Part of the trick of what makes a Gen-12 shoot so softly is the barrel recpirocates, but that also means muzzle attachments such as suppressors or breaching devices risk shifting the timing of the shotgun or it simply not working at all. That funky bit you see on the end of the barrel is in this case permitting the attachement of Remington-patter chokes, 5 of which are included with this gun.
Who's it For? If it was your assumption that the Gen-12 is best sooted for defense, agency, or military use you are correct. The development of the front mounting system was meant for suppression or breaching, but has also allowed a choke system. This gives the Gen-12 a sporting application for flying targets like those we've heard so much about in recent news from Eastern Europe. You may be quick to say that a conventional shotgun might do the trick, but the flocks and speed of those birds may require more rounds or a bigger variety of ammunition than standard waterfowl.
Take a look at the Genesis Arms Gen-12 SSBM in the quick intro video below (Rumble Link)
This particular example is a blend of the Dual-Charging Gen-12 SBM (breacher) and the choke system yet to be listed on Genesis Arms' website. Specifications below are for the Dual Chargin Gen-12 SBM. For pricing on the choke system please contact Gensis Arms.
Specifications:
FEATURES
10.5” barrel length
Chamber 2 ¾” and 3” 12 gauge shells
Muzzle Thread: 1 3/16 - 18
Ported Muzzle Device
Short recoil operation
Free float handguard with M-LOK® rail at 3, 6, 9 o’clock and full picatinny top rail
Dual side charging knob
GEN1 DPMS 308 patterned lower
Mil-spec buffer tube
308 short carbine buffer 3.8oz
Hogue rubberized grip
Milspec AR Trigger
INCLUDES
5-round magazine
Soft case
Limited warranty
The Magazines are one of the key developments making the Gen-12 possible. While there are many AR-looking 12 gauge platforms out there, those aren't using a true DPMS Gen 1 pattern AR-10 lower. The problem comes from the rimmed 12-gauge cartridge which does not like to behave well when stacked vertically, especially through the top of the magazine which must be straight to fit the AR pattern. Do not be fooled by look-alikes. Genesis Arms has pattented this magazine design. Additional magazines are reasonably priced (speaking from the perspective a former Molot Vepr 12 shooter) at $24.99 for a 5-round and $39.99 for a 10-round. Contact Gensis Arms for a limited hunting-legal magazine.
How does it work? The Genesis Arms Gen-12 works on a short recoil system. The barrel reciprocates shortly before the continued momentum of the carrier, via a cam like an AR, causes the bolt to turn and unlock like an AR. This process, plus a hidden trick discussed later, and an AR 308 buffer and recoil assembly makes for a very soft-shooting action. As you'll see in the video below, the Gen-12 can be run about as quickly and flatly as you would a well-tuned AR. I'm not exaggerating. It's not as soft as a 5.56x45mm AR, but softer than many .308 models I've tried.
By this point I'm sure you're wondering how well the Gen-12 runs, and if such a short barrel is even practical for aerial targets, even with chokes. Do the AR-like controls offset the extra heft that comes from large-frame AR receivers? See the Shooting Impressions video below which includes my first shots, a variety of ammunition from low-speed, lightweight bird shot up to 1 1/8oz slugs, and self-flinging a clay and attempting to engage it.
As you saw I was impressed with the Gen-12 SSBM. That is significant, because after six years of following development and shooting various generations of the Gen-12 I was always previously impressed and each time though the system was as good as it could be.
If you noticed that the heavier/hotter the load I fired, the gentler the gun seemed to run, I believe I understand how that happens and it's part of some of the newer evolutions of the Gen-12.
Tucked under the hand guard is a counter weight system under spring pressure. As the barrel begins to recpirocate rearwards this counter weight wants to remain in place relative to the barrel. The harder the barrel cycles to the rear, the harder this weight moves relatively forward; effectively reducing some of the potential slam of the barrel at the end of its motion, and slowing some of the unlock. This is all just my semi-educated guess, but this development is new since my earlier Gen-12 reviews.
The Gen-12 is not inexpensive, and over the years I've heard many be critical of the price. Arguments like, "That Turkish gun looks similar for a fraction of the cost" are all over the web and do have merit. They do look like an AR, and they are much less expensive, but that's because they're not an innovative platform, made in America, and not compatible with a .308 upper. They also don't last as long or have the same capabilities or attributes.
Make no mistake about it. The Gen-12 has been developed with duty use in mind, and evolved based on feedback from serious professionals. Those alternatives were made to create an appearance and while they may function sometimes for a while, they're not going to last and would be a liability during serious use. See any of TFB's burn downs to watch those guns fail. Meanwhile I was present for a full day of full-auto fire being run through a short-barreled Gen-12 and aside from expected suppressor fouling, the gun kept running.
About Optics: You may have noticed that for the first time in a Gen-12 review I've got an Eotech mounted. This was recommended to me years ago by the crew at Genesis Arms, but not only are EoTech's out of my usual price range, I also wanted to believe in and try other optics.
Those other optics survived the rapid action of a Gen-12, but their mounts did not. The taller the mount or heavier the optic, the more force is applied to the base of the mount. EoTech's build style and mounting strength has prooven itself at the many range-day demonstrations Genesis Arms has participated in. When you get your Gen-12 I too now recommend going with an EoTech. As an added plus, the circle-dot reticle seems to make engaging aerial targets easier.
man... it must be nice to be able to afford something as sweet as this is.