Patent App For Bullpup Shotgun Conversion Kit

James Hunter, Hank Gevedon and Rex McDonald have applied for a patent (#20110283582) for a bullpup conversion kit for Mossberg 500 and Remington 870 pump action shotguns.

Cutaway with the shotgun action highlighted in red

Rex McDonald and Hank Gevedon own PD3, a Kentucky company dedicated to helping inventors bring their ideas to market.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Other Steve

    That’s fairly cool. I would prefer Ithica or Browning style bottom eject, but those are nowhere near as common as 870/500s.

    Bullpups are almost always a miss in the style department, with notable exceptions being the AUG, RFB, and KSG, and a couple others. If they could make it look good and lightweight I could be interested in this if it ever makes it to market.

  • Mossburg made a bullpup shotgun, I remember when I had a shop I couldn’t give them away. I had always been of fan of the High Standard model 10 and 10B so I stocked up on the mossburgs anticipating expecting big sales.
    Buy high, sell low that’s my motto, I have always told people the best way to have a million dollars and a gun shop is to start with two million.
    I wish the gentleman good luck in this venture, maybe the time is right for it now.

    • cc19

      I remember the Mossberg bullpup. They even had some Hollywood screen time back in the 80’s. Recently, they ask for a pretty penny these days since they’ve been discontinued all those years back.

  • Matt G.

    Looks sexy. If they make it cheap I’ll buy one.

  • Lance

    Looks fun but not really a need in the field for one.

  • That’s definitely interesting. I don’t have a use for it but I’m sure someone does

  • CrCobb

    If the price is right. And I’d like to know something about the trigger linkage, but I’d accept mushy as a trade off for short and still controllable (not pistol grip only).

  • Jason

    Why don’t they make a bullpup kit for semi-autos? I don’t get they they’re always pump-only. It’s not the 1950’s anymore.

    • Most semi-auto shotguns have recoil spring housings that extend behind the receiver into the stock. The bullpup conversion stock would need to be longer to accomodate this.

      • Tinkerer

        Not all. Some very nice gas operated self loaders have the spring around the magazine tube -which also act as a guide rod for the annular gas piston that push the operating rods -in a nice long stroke gas piston setup, with no buffers on the stock whatsoever. Those shotguns are perfect for bullpup designs. Think High Standard 10. I believe that Remington 1100 and 11-87 work on this principle, as well, but I can’t confirm that.

      • Tinkerer: The Remington 1100 and 11-87 have recoil spring housings in the buttstock, as have most of their other semi-auto designs dating back to the original Model 11. The latter was their licensed version of the Browning Auto-5.

        I know that the 1100 and 11-87 can be gunsmithed to reposition the recoil spring (e.g., the Sage Int. Sidewinder), but this defeats the ideal of a drop-in stock installation.

        Are there are other semi-auto designs that wouldn’t require this level of gunsmithing? Certainly, but they aren’t prolific enough to support an aftermarket bullpup stock.

  • Wayne

    I’ve got a personal and a tactical beef with right-ward ejecting bullpups of any sort. I’m left-handed for one thing, and for another, it seems for a tactical longarm, you should be able to fire it from either shoulder. Not a possibility with side ejection.

  • M8R

    To my untrained eye that looks like the stock from:

    but I could be wrong . . .

  • charles222

    Yeah-is there a similar kit for a bottom-ejecting shotgun?

    I remember the old Mossberg bullpups as well; weren’t they marketed under the Maverick brand?

  • JamesF

    I do believe that this patent is for the Bullpup Unlimited conversion stock that M8R linked to.

    If it is, then I’ve actually fired a pre-production version at the annual Bullpup shoot in IL. I got to fire it alongside a Kel-Tec KSG, and I liked it quite a bit.

    The KSG had some issues, but the Bullpup Unlimited conversion ran and ran.

  • Big Daddy

    I looked at some pictures of it and even before that the first thing came to mind….HEAT. It’s a gun encased and to me that means it’s going to be hot, the encasement holding in the heat. There does not look like any venting.

    A bullpup design has a certain coolness to it but not that type. Plus I would not want a 12 gauge chamber near my ear or head for that matter.

    For the advantages it has the disadvantages are more.

    • charles222

      It’s a pump-action 12-gauge. It’s going to take quite a while to heat up.

  • I found this article while checking to see if anyone else had already thought of my great “idea” for a shotgun mod. DA FAQ?!