Weld your Own AR-15 from Flat Spot

For the ultimate do-it-yourself-er or someone still waiting on their Ghost Gunner, The Flat Spot has a nifty weld-your-own AR receiver out of mild steel. The kit is not 100% weld and go, as it does require some work.

5058979_orig 6057196_orig

Details on construction for The Flat Spot:

AR-15 RECEIVER FLAT(weldable) mild steel construction for $28.00 Combine with other products we offer to save. $6 unlimited flat rate shipping. Please note – these are for builders and still require some work IN ADDITION TO WELDING such as tapping of the buffer tube hole (many builders choose to simply weld a castle nut on the rear of the buffer tower instead of tapping), drilling détente holes, drilling bolt release pivot pin holes and some fitting.  Note – tap and drill holes prior to assembly. ** The builder must insure the finished receiver is functional as SEMI-AUTO only.  If you don’t understand this concept do not order this item **  Deburr the tab from all parts to insure proper fit during assembly.  Please see the cad drawing files below for assembly instructions.

The kit is available for $28 with $6 flat rate shipping. Many other kits are also available including parts for AK’s, UZI’s, and MAC-10s

Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • BrandonAKsALot

    They seem way easier than they are. It’s usually quite a challenge to finish one and if your tooling is limited, then you have to be creative when it comes to the takedown pin detents and bolt holt open pin hole for example. They are a good starting place for custom builds though and can serve as a trigger pack or magwell.

    • patrickiv

      I agree. I got about 25% through one and realized how much work it would be. It would be better if the pieces were notched like a finger joint to help with alignment. These require good welding skills that I just don’t have yet.

    • Booger Hook

      Wing nuts and bolts for takedown pins
      Safety? Meh. Glocks do fine without a manual safety

  • Christian Hedegaard-Schou

    Huh… I like the idea of just welding a castle nut to the back. I guess you could use a second as a lock nut to prevent the receiver extension from rotating. Or lots of red loctite. Or both.

    • Roger V. Tranfaglia


  • Sianmink

    Just slap some JB Weld all over it I’m sure it will be fine.

    • Dan

      You sir win the internet for today.

    • Roger V. Tranfaglia

      I. WAS going to say gorilla glue…or even DUCT TAPE…you beat me to it…

  • dan

    does any one have any links/info for me if i wanted to build an ar15 completely from scratch including the internals?

    • Dan

      Nice name ya got there

    • BryanS

      Easy, get a couple blocks of steel, some aluminum, and remove everything that is not an AR.

      There is also google.

  • BryanS

    Debur? Hell, toss it in a tumbler for a day beforehand.

    that’s going to be hard as hell to weld without warping. Someone out there should figure out a rivet build!

    • Westin

      Depends on the granularity of your heat settings, I’ve had two different MIGs that could do 1/2″ without breaking a sweat .. and then turn down to weld together razor blade edges. Think “not-Harbor Freight”

      • BryanS

        Harbor Freight only enters my mind (in welding) for things like cutoff discs, because lowes is out.

        No matter what, lining it up and keeping it from warping will take a long time.

  • Budogunner

    Why the hell do these exist? You can get a completed stripped lower for less than $60 these days. If you want DIY, an 80% would be much easier.

    • Steve Truffer

      Because you get more pride in craftsmanship out of it. You can finish an 80%, or you can make this.

    • marathag

      So you can Blue it, rather than coat/anodize/paint

      But it won’t be a nice bluing, because welding.

      But that’s life. Why ask why? maybe somebody has an urge for a lower that you can stick magnets to.

      • Budogunner

        Ah, now I understand. It is the Rick James + couch philosophy of gun building.

        You can build a F*cked up lower for less than $40, then tell your wife, “but honey, I already bought ALL the other parts. I just need to replace this messed up lower with a biller lower by Spikes Tactical (or insert your favorite premium builder here).”


  • Cornelius Carroll

    Tapping the buffer tube is a deal breaker for me. Like the concept though.

    • MR

      Could just weld on a flat plate for a dedicated 22lr build. If they make 22lr anymore.

  • Scott Tuttle

    they need to put up a video ‘how to’

  • iksnilol

    Doesn’t it weigh more than a regular alu receiver?

    • Aurek Besh

      Yes, however aluminum is significantly more difficult to weld than mild steel.

      • iksnilol

        I know, I just find the idea of the sleek, aircraft grade black rifle made out of steel to be funny.

  • Marty Ewer

    I like the idea of these. But I’m a terrible welder. That’s why I pay someone to weld for me.

  • andrey kireev

    InB4 media spasms out about un-serialized pieces of metal anyone could turn into a functioning firearm. /MDA twitter messages .
    InB4 ATF issues another stupid opinion letter that makes no sense.

  • Ron Fox

    Yeah but will my harbor freight 120V mig welder do a nice enough job? Haha, no way in hell.

  • Roderick Lalley

    Screw it together !!!

  • Martin M

    How much does it weigh being made from mild steel?

  • DIR911911 .

    just remembered I have a buddy who welds over at great dane , have to see how his skills have developed.