80% Build, 25 Round Semi Auto 12ga Shotgun Kit

update, Sunday 24, February 5:18pm:  Part II of the concept prototype build is up: FU25-12: 12 Gauge Auto Combat Shotgun Build: Part II


With the advent of the 80% home built weapons market becoming so popular, and the sublime freedom of making your own personal arsenal, has inspired me to create weapons of my own design.

The 12ga weapon pictured below is of my own design, a 25 round “Feed Tray” fed, gas impingement operated, semi auto shotgun.

It is constructed almost entirely out of chrome moly aerospace specification precision tubing and bar stock. The design incorporates a number of AR10 and AR15 components, such as buffer/spring system, trigger/safety group, a modified 80% forged AR15 lower receiver, these are proven reliable components, making the entire design much less complicated and is of a great savings in materiel costs and labor.

No promises, my intent from the beginning, and many factors could easily change this, to offer an 80% kit somewhere around $550 bucks plus shipping. I got to make a few bucks on each kit to make it worth the labor and materials. I’m not into it for money. It is something to accomplish, do my part lets say in regards whats coming down the pike. This is a true dirt people project, start to finish. Just a guy in his shop who loves him some Liberty and self determination. What better way than being a backwoods mountain gunsmith in West by God Virginia.

[FYI, I have a few kit weapons designs for future development, one of which is a .50 cal Ordnance Browning single shot rifle in an 80% kit form, I’m hoping it can be offered for under a grand. Thats a tough goal, but I have some different ideas on a .50 regarding how it is constructed which will keep materiel/labor costs to a minimum. We will see. The FU12-25 proceeds will go towards developing the .50cal single shot kit.]

The FU12-25 “Feed Tray” feature, is a captured double row single feed, 25 shot shell capacity, magazine, with a quick release lock on slam, closing provision, allowing for the operator to replenish his ammunition without the typical magazine swap of most magazine fed weapons. No magazines to handle, need for very large, heavy and bulky foot long large capacity mag pouches taking up valuable MOLLE real-estate. You get full time tactical reload capability without dropping a mag, while a shell is chambered, or bolt locked back.  How to manage reloads can be accomplished in a surprising number of practical ways utilizing current off shelf gear. More on that in later news as the project proceeds.

The sketch below is a rough draft of the concept. Currently I am in the process of fabricating and machining an R&D model for testing & evaluation. The basic form will not depart much from the rough draft drawing below.



One of the ideas which have come out of the original thinking of the weapon, is to offer it in an 80 Percent “Kit” form. It may be comprised of a kit in a semi completed set of sub assemblies state, requiring basic steel welding, along with required machining which can be accomplished using common metal fab/machining resources used in the making of AR and AK platform 80% builds.

This is a brute of a weapon. There is nothing GUCCI, graceful, or phoo phoo about it. It is a down and dirty, so ugly its beautiful, pre CNC era, metal fabrication and machining produced weapon. Built to be rugged, reliable, lethal. You can see for yourself it has a certain Karl Gustav Sten sub machine gun style to it. The design is on purpose, as much as form follows function as it gets. Its not called the FU12-25 for nothing.

If the bolt/gas impingement Feed Tray engineering works out without encountering unusual R&D problems, I hope to have a fully working beat to shit reliable weapon ready to begin offering 80% kits by spring. The devil is in the little details. I have a basic metal fab shop. Been a welder/fabricator, basic machinist for 43 years. I’m a frugal sonofabitch, old world metal craftsman, less is more, common sense and absolute reliability, no bullshit kind of guy. If I am able to make this work within the realm of following those aforementioned criteria resources and my skill sets. it should be a weapon of robust reliable lethality.

I’ll post photos at various stages of the R&D unit.

If I can produce an 80% kit and your interested in obtaining a kit for yourself, leave a comment.

Thanks much for checking this out.


PS, ASAP I’ll make a complete FAQ like list of the features of the FU12-25 as time permits. There are some features which only can be settled on thru R&D. 

Part II of the concept prototype build is up: FU25-12: 12 Gauge Auto Combat Shotgun Build: Part II


12 thoughts on “80% Build, 25 Round Semi Auto 12ga Shotgun Kit

    • Me too pal. Thanks for your interest. Appreciate you.
      The only part of the design that requires developing something unusual is the gas impingement assisted locking lug, blowback bolt system, and the bolt mass/buffer/spring assembly packaging. Have a rough calculation of mass and spring rate needed, the AR10 buffer & spring looks close, the fine tuning is a matter of finding the suitable bolt mass. The AR rifle buffer provides a range of mass adjustment. Stoner’s rifle buffer design of rebounding free floating inner weights you can change out is a superlative setup. There’s a whole range of buffer spring rates available also. Doesn’t get much easier R&D than this.
      Everything else is essentially repackaging proven ideas and components.
      The only really unique part is the overall concept, which again is form following function, (and materials use to a certain extent), and the shot shell “feed tray” which swings out to reload, and its lock closed on slam feature. Its intuitive to operate, and iterative as you reuse the magazine by the feature of being able to refill it at any time. A 20-25 round conventional shot gun shell magazine is like a third leg they are so long. How do you carry a full combat load of those large magazines in the practical sense? 20, 12ga, 2.750″ length shotshells double row stack up in a feed tray requiring inside dimensions of 9.250 inches long x 1.590 inches wide, plus follower. I’m using two coil compression springs with lifters using a relatively thin follower, the spring assemblies ride in galleries located outside on each side of the feed tray. I don’t need as large a take up space below the shell follower for a standard inside magazine spring, helps keep the overall length down this way.

      Trying to avoid in every way possible re-inventing the wheel. Using a lot of bits, or repurposing those bits from the AR platform. Proven stuff used within their design limits.
      The fabrication, weldments and machine work is basic, pre NC/CNC, old timey hand screw lathe and Bridgeport mill work, tube fab, and GTAW fusion steel alloy welding.
      The chrome moly aerospace tube stock comes in high precision sizes, eliminates a ton of work, it is superb material for this purpose. Its yield to tensile, and wear characteristics are world class, and allows for rather thin wall thickness’s providing for a light weight assembly. It was designed for aircraft, its proven itself since the late first world war.
      I’m using many features of the AR, modified to suit the design and shell, that alone makes the design about as easy to manufacture I could figure out. I have two alternative bolt/locking/buffer ideas to fall back on if my first choice doesn’t work reliably.
      Reliability is my #1 goal, everything has to follow that.


      • You definately sound passionate, for good reason, I might add. I have to admit I’m having a bit of a problem picturing in my minds eye just exactly how the shotshell magazine/carrier is going to function. Some sort of locking mechanism to hold the spring(s) down for re-loading? Some sort of hinge system with a snap lock to open the magazine?

        Liked by 1 person

        • Best way I can describe it to you, till photo’s are posted, is its fairly basic. Think the concept of a tube magazine fed shotgun. Now arrange this tube mag so it works feeding shells from under the bolt, instead of down and in front with a lifter mechanism, ending up in a form like a drop free rifle magazine, but captured at suitable pivot points, with a swing away feature so you can put new shells in any time, the early push it back into position where it automatically lock, as a drop free mag does but it is pushed up towards the bolt. The “feed tray:: pivots outward perpendicular to the barrels axis, (sideways, left or right side, if I can develop a locking device you can set up to your choice of direction of opening), feed tray opens enough so the feed lips clear the upper receiver where the operator can replenish the feed tray with new shells. A spring loaded, finger actuated locking pin within the trigger guard releases the feed tray, which is pulled with hand remaining on grip, is pulled to unlock. On closing the operator “slams” the feed tray into the closed position, or battery. No other action is required as the locking pin has a slam lock feature which activates when the feed tray comes into operational battery position.

          Operator loads the feed tray as with any spring and follower magazine.

          The feed tray is double column, permitting a higher round count without the very long magazine length say a single column drop free magazine the 12 gauge SAIGA uses.

          The entire weapon system is predicated on simplicity and reliability. The form it takes is organic to its function, and the use of a variety of already proven existing components from other proven weapons, employed and packaged accordingly to function within the FU-12’s concept.
          Nothing is of the re-inventing the wheel design. In other words re-purposing reliable, cost effective parts and designs.

          I believe the most difficult aspect of development will be fine tuning the gas impingement and impingement actuated locking lug, and the bolts mass, plus buffer mass, and buffer spring rates.
          The function of which is a gas impingement “assisted” – delayed, blowback system. Because of the relatively low pressure in LUP, and the heavy mass of the payload, using either the gas impingement, or blowback, there’s too many shortcomings to work past. Using both, one eliminates the others designing drawbacks. Reliability is the driving factor, it is the design criteria. Everything else follows. No skimping on this or the design won’t work.
          That is my engineering style here.

          The feed tray being a shot shell double column design will probably go thru a number of iterations before it is producing reliable strip and feed.

          There is a number of items will only be determined via a working prototype. Nothing unusual there, essentially hard work and attention to detail. Id say the only thing unique here is the entirety of the package. A different concept from current shot shell semi auto combat weapon convention. And in no uncertain terms, this is a combat weapon period. Fun factor though? That is a really subjective element. Though again that is a form follows function thing in itself.

          To compliment the combat nature concept, I am in the process of developing a dedicated pouch and chest rig to compliment the FU-12’s unique combat envelope.
          Being it is a combat shotgun, with a very high capacity, naturally this requires the carriage of unusually high number of 12 gauge shells for reloads to stay in the fight. 50 rounds of reloads aint gonna cut it.

          Typical drop free magazines would take up too much MOLLE real estate, never mind empty magazine weight, to approach the shell count possible using “loose” shell pouches. Actually the pouches in mind hold either the ESSTAC shot shell card system, or shells retained in elastic loops. But conformed in such a manner as to provide unusually high shell counts, designed to be easily manipulated under various combat conditions like in the dark, mud, snow etc in the prone, or other body positions under high stress.

          Trying to design a total, and holistic system here, again form follows function. In a “kit” form the home workshop regular Joe can produce.

          Nothing says unfettered economic Freedom and the blessings of Liberty than one Man making his own arms. A nation doing this? That shit rocks.

          It was this way in the past. In Colonial our era, and beyond, home workshop, and small craftsman operated shops, produced rifles of the highest regards in a number of aspects.
          There is an entire movement of reproducing the craft work of the Colonial era. These American’s are producing works of art you have to see to grasp the level of quality and execution of craftsmanship.
          Here is a link to a very fine blog dedicated to this community:
          Contemporary Makers

          Why not a grass roots modern Arms “Makers” movement?
          For proper and legitimate reason too. The advent of the 80% firearm and the build community that has arisen is a great and world changing event. Think how many have withdrawn their consent for the government and its actors who are trying to take our property, our guns, and turned to building their own.
          Nothing says Liberty, and BFYTW, like producing a rifle with your own hands.

          So there is your passion right there.
          I believe our Arms are second to anything as it pertains to our Liberty and unfettered economic activity.
          Without these two essential elements of Liberty, we are not Freemen. Building your own is the combination of the two.
          We all who care for our freedoms should all undertake to build our own arms if for only this reason.
          It is a way we can peacefully yet resoundingly reject, and resist tyranny.
          Not much else sends that kind of message.


  1. I’m very interested, and intrigued! I have been a machinist in a former occupation, and have some good and appropriate tools in my shop to work with. I’m used to working off blue-prints & machinists drawings… (former airplane fiixer). I’d be happy to assist.

    Liked by 1 person

    • Maybe we can work something out.
      I got to think how to describe what your part of the deal would entail exactly.
      It is specific for particular reasons having to do with the 80% kit concept.
      I have a specific purpose in mind with this project, and that afore aspect is very important to me. Its why I’m putting the effort into this to begin with.
      there’s the fun factor, and the combat intension, “because I can”, the 80% thing is the prime motivation. If what I’m intent on accomplishing is successful, great, to do that an entirely independent builder with no ties to any arms manufacturing, or the gun press, a regular every day Joe who loves him some home made weapons.
      If not I’ll have me a home made one off, unless somebody is interested in the design or some kind of investor thing. But that last is not part of my plan here.

      Ineed a guy to just build it, have a functioning reliable weapon, he did on his own druthers. Long as it is an organic build he accomplishes individually. And puts in an honest and honorable effort to spread around the features and viability of the 80% kit build at by home workshop resources.

      Hard to explain exactly, but its about self reliance, self determination, the unfettered freedom to do such a thing as free people living free without the meddling and other intrusion of government in our personal affairs.
      Maybe that sounds too deep, or corny. But there are very important elements and precepts involved, things I personally believe can be exemplified by the actual doing, The Act, as in it is the act which matters.
      To add to that what is more pertinent to our natural born freedoms and Liberty than manufacturing, or crafting if you will our own arms.
      I think too, nothing could peacefully re-enforce these precepts and ideas better than in this manner.

      Make sense to you?

      I’m looking around me, and personally participate, in the renaissance of personal arms taking place. It is totally awesome and like the axioms tells, “we have to learn to drink from the skulls of our enemies again”, the premise in that is what better than to become the citizenry warriors of our great Christian Greco/Roman Western culture and and history, once again, than to be men, warriors who also make their own weapons?

      This isnt about making a profit, or even a money thing. All though, I’m a working stiff recently retired, I do have to recieve a certain monetary, or barter compensation to pay for the materials and a humble stipend for my labors and overhead, partly so I can do the same with other weapons concepts I have come up with.
      This is about something larger than only you or I. The imperative is it all begins with each of us, passing it forward too.
      Hopefully your getting what I’m driving at here.
      In every way this is a grass roots effort. Keeping it grass roots, open source, its the main idea. Its symbolic and actuary. The weapon is secondary to that. Not that the weapon isnt as important, its just important in other ways. Our guns are very important.

      You know what “MYOB!” is about?

      Here’s where it comes from:

      BFYTW comes from the same place.
      So does the FU12-25.
      Lot of things do.
      Like The Honorable Resistance or Come and Take Em’


  2. Pingback: FU25-1212 Gauge Auto Build Part II | Dirt People

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s