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Plans full auto co2 bb "usi" submachinegun

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  • Wirecutter
    replied
    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

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  • Mortimerex
    replied
    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.

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  • Mortimerex
    replied
    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.

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  • Mortimerex
    replied
    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.

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  • Mortimerex
    replied
    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

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  • lazlo
    replied
    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.

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  • Nick Carter
    replied
    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.

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  • tsmartin_98
    replied
    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

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  • slayer666
    replied
    I'd be interested.

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  • Mortimerex
    replied
    Haha, I'm not selling anything here. You guys are too cheap. If it don't sell at all, then I may give the plans "as is" which is what I used to actually build it. The only charge would be if you want me to clean up the drafting so it looks pretty enough to satisfy a moderately leanient drafting instructer (which I was once at ITT- not my alumni just where I worked as a drafting & design instructor while working on a Masters degree I never finished).

    I do have a design remarkably similar to that Russian one, even with similar placement of mechanisms and with an electric motor too. But it was for a thompson "tommy" looking carbine size machine gun (although actually it looks sort of like a cross between a tommy gun and an m4 carbine). I want to try out the simple, small, purely mechanical, submachine gun first, only problem is my mini-mill & lathe may not be up to making the only 3 tolerance (and friction) critical parts in this design. In which case I will probably just go with the tommy gun.

    If I could mass produce the "usi" submachine gun (acctually was gonna call it the "Box Mag" first for obvious reasons -but I put a little 2hand grip and milled a few cuts and it now looks remarkably like an "uzi") I may theoretically be able to sell it for around $50 depending on the difficulty of making those few critical parts. This is theoretical, as I don't plan to mass produce anything unless I can get some high bid wars going on e-bay.

    I may mention it here if one sells for some preposterously high amount just to gloat tho.

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  • Guest's Avatar
    Guest replied
    Well, now that you have crossed the line....
    THERE IS NO SELLING OF PERSONAL STUFF HERE!

    I wouldn't have said a thing about it, But without even seeing the other gun you think yours is better.Thats not what we are about here.

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  • Mortimerex
    replied
    Originally posted by Nick Carter

    Nice but I bet that has about 10x more parts than mine. Also, my design is fully mechanical. Don't see any price on it. Even hand crafting, mine should be around $200 each (to pay me minimum wage). Hopefully selling in small quantities on e-bay the price for mine may go alot higher. Also, you don't know who designed and makes that Russian gun. Doesn't mean its not good or bad, just that you know mine was designed by an engineer with a Bachelor of Science in Mechanical Engineering (from a top 10 engineering university - top 10 in the world.) I was hoping I was the only one working on something like this. 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.

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  • Guest's Avatar
    Guest replied
    I will stick to the easy ones....
    http://www.burntlatke.com/bb.html

    Both of yours have a small, limited BB supply. This design,is only limited by your own design,and weight restrictions.
    As for air supply,a 5# co2 fire extinguisher regulated is fine.

    I have owned the Lark, Drozd, and others from various mfgrs.

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  • Nick Carter
    replied
    Have you seen this:
    http://makarov.com/drozd/index.html

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  • Mortimerex
    replied
    Originally posted by flatlander
    hornluv,
    We played the same game at our state fair in Hutchinson, Ks. 36-37yrs. ago. The guns in the booths there were modeled after Thompson submachineguns. I think they were using #7 or #7-1/2 soft lead shot in them - if it'd been steel shot, there'd have been shot bouncing back at all the rubes trying to impress their girlfriends. I've often wondered where all those neat old subgun airguns wound up; it'd be fun to take one apart and get a good look at the mechanism.
    They're probably illegal now (for carnival or residential areas) which is why I plan to sell them on e-bay. The mechanism can be quite simple if you understand the physics. Its not alot tho, only about 6 pages of calculations describe most of what I expect to happen. The 400fps is based on 100psi air compressor which I plan to do initial tests with. Don't know how many psi the cartridges have but I suspect it may start out producing like 600fps muzzle velocity and drop as the cartridge discharges.

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