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Plans full auto co2 bb "usi" submachinegun

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  • #16
    Originally posted by Mortimerex
    Oh well. I'm still going to finish mine (about 2 weeks) and at least try selling one on ebay. If the gun works well but selling it doesn't work, I may make the plans available for a small charge.
    Better make it an airsoft then, Ebay doesn't do BB guns:

    Prohibited and Restricted Items> Firearms, Weapons and Knives:

    BB Guns, Replicas, Blank Guns and Imitation Guns: eBay does not permit the sale of BB guns, air guns, black powder guns or muzzle-loader guns, and does not allow sellers to use the term “BB gunâ€‌ in the item title or description of any listing. eBay permits paintball guns, "airsoft" guns, and replica, "look-alike," and imitation firearms under certain circumstances. These items may only be sold domestically in the United States provided that they have clear markings permanently affixed to them (commonly a blaze orange plug inserted in the barrel), and must not be readily convertible to shoot a projectile. This includes replicas/imitation guns of any age, as well as toy and cap guns. These items must be located in the U.S., offered only for domestic shipment and the seller must be located in the U.S. These rules apply to all items designed to look like firearms. Most states require that purchasers of airsoft guns be 18 years of age or older.
    Largest resource on the web for Taig lathes and milling machines, www.cartertools.com

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    • #17
      Originally posted by Mortimerex
      Anyone interested in plans for a full auto bb submachine gun with the following specifications? (The prototype isn't quite complete yet so the specs aren't locked in)
      Very neat! That reminds me of the old days at the carnival where they would have full-auto BB guns, and you would get a prize if you completely shot out the black bull's eye. Of course, no one ever did (at least, no one I knew ever did), but it was sure fun spending a lot of quarters trying

      I'd definitely be interested in purchasing your plans, if you're confident the prototype works

      Edit: sorry hornluv -- didn't catch your post. Yep, we had them on the Wildwood Boardwalk back in the 70's. Looked like Thompson submachine guns like flatlander described.
      Last edited by lazlo; 08-07-2006, 09:55 PM.
      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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      • #18
        So no ebay for bb guns Well, something similar. I'm sure there is some e-bay type setup that isn't run by anti-bb gun nazis
        “It was not til Leibniz and Newton, by the discovery of the differential calculus, had dispelled the ancient darkness which enveloped the conception of the infinite, and had clearly established the conception of the continuous and continuous change, that a full and productive application of the newly found mechanical conceptions made any progressâ€‌

        Hermann von Helmholtz (1821-1894)

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        • #19
          Originally posted by tsmartin_98
          Yours looks better than the ones my friends and I bought back in the mid 70's I think. They were pretty cheesy and not well constructed but they were cheap. I can't remember how much they were but we bought a lot of them.
          We soon ditched the CO2 cartridge for a 120 psi air compressor. You'd go through 500 BBs in the blink of an eye but it sure was fun while it lasted.
          TS

          Sounds good. I wish I'd got a tommygun back when they were around, even if they were junk. My prototype has both c02 and an npt air compressor inlet although I was planning on ditching the npt after it goes gold. It will be in the plans so you can put it in or not.
          “It was not til Leibniz and Newton, by the discovery of the differential calculus, had dispelled the ancient darkness which enveloped the conception of the infinite, and had clearly established the conception of the continuous and continuous change, that a full and productive application of the newly found mechanical conceptions made any progressâ€‌

          Hermann von Helmholtz (1821-1894)

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          • #20
            Originally posted by lazlo
            Very neat! That reminds me of the old days at the carnival where they would have full-auto BB guns, and you would get a prize if you completely shot out the black bull's eye. Of course, no one ever did (at least, no one I knew ever did), but it was sure fun spending a lot of quarters trying

            I'd definitely be interested in purchasing your plans, if you're confident the prototype works

            Edit: sorry hornluv -- didn't catch your post. Yep, we had them on the Wildwood Boardwalk back in the 70's. Looked like Thompson submachine guns like flatlander described.
            Within about 2 weeks I will be confident -that it either works as intended, goes back to the CAD lab, or gets trashed. Its starting to come together fast now. The design is 95% done, just need to put in a safety and finish up the trigger assembly, and detail the speedloader. Then if it works good with the 30 round box mag I gonna go ape on the 300+ round mag (which isnt nearly as big or awkward as you might think for a drum mag- a little smaller than a cordless drill battery pack).

            An update on the muzzle velocity. I don't have any instruments to actually measure that but based on calculations (neglecting friction) v= 760fps. I ran the calculations on a Daisy Powerline XT which I measured barrel length of approx 4" and a claimed v of 410fps, I got 536 fps at 100psi. So friction, pressure, or barrel length measure error gives a -23.5% efficiency. So I "corrected" the usi v by that amount to get approx 580 fps. Thats probably as close a result as possible for some time.
            Last edited by Mortimerex; 08-08-2006, 02:17 PM.
            “It was not til Leibniz and Newton, by the discovery of the differential calculus, had dispelled the ancient darkness which enveloped the conception of the infinite, and had clearly established the conception of the continuous and continuous change, that a full and productive application of the newly found mechanical conceptions made any progressâ€‌

            Hermann von Helmholtz (1821-1894)

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            • #21
              Heres a link to something similar functionally to what I'm working on.

              http://www.bloomautomatic.com/bbmg

              Cost is over $250 and it doesn't even look like a gun at all. Looks more like a something you pound in the ground or attach to the toilet plumbing. Haha.

              I redesigned my "usi" yet again reducing number and complexity of parts. This is alot closer to a final design, probably won't be any more major changes now. Even with all the effort to keep the design simple and sturdy it still takes time to machine it all. Of course, if it works like expected them I can try molding parts once I'm sure everything checks out. Several assemblies consisting of 3-10 parts can actually be made as a single molded plastic part requiring only parting line sanding and minor clean up with no machining at all.

              Finished the new 30 rd removable box magazine today, may show some pictures but its basically just a box machined from acetal plastic. I found that using a coarse end mill provided a very nice non-slip grip surface, I wonder if that surface texture will transfer to the molds? Would be nice not to have to machine any more mags, just mold em by the dozen (perhaps out of recycled soda plastic even).

              Also, started on the drum magazine design.
              http://img.photobucket.com/albums/v1.../usi_frame.jpg
              It looks like I can make a 100-200 round drum mag that is actually less cumbersom than the 30 round box mag. One drawback to using the same design that the box mag uses is that there will be around 20-30 rounds that never leave the clip, but that is a minor defect considering it will increase the overall magazine capacity (without having to redesign the whole gun) so much without having the drum magazine in too awkward or cumbersome orientation.
              “It was not til Leibniz and Newton, by the discovery of the differential calculus, had dispelled the ancient darkness which enveloped the conception of the infinite, and had clearly established the conception of the continuous and continuous change, that a full and productive application of the newly found mechanical conceptions made any progressâ€‌

              Hermann von Helmholtz (1821-1894)

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              • #22
                My younger brother had one of those CO2 powered automatic BB guns - .177, IIRC. It was a hoot to shoot, and could really hose and area down with BBs, but the worst injury it could inflict was probably to sting or welt bare skin. The kids would put on safety glasses and a raincoat and shoot each other until the CO2 ran out.

                I still remember slipping on the BBs all over the garage floor.

                -Mark
                The curse of having precise measuring tools is being able to actually see how imperfect everything is.

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