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Thread: Wanting To Build A Simple Pistol

  1. #21
    Join Date
    Sep 2008
    Central Kentucky


    Quote Originally Posted by Joel View Post
    What part bent?
    I would definitely like to see some pictures of your and everyone else's builds!
    Not a pistol but here is a rifle I just finished a few weeks back, it's the third one of the same basic design, based on the 1885 Winchester.

    :EDIT: Well I will post the pics when I can get them to post!
    Last edited by radkins; 07-16-2018 at 10:02 PM.

  2. #22
    Join Date
    Apr 2007
    South Texas


    Quote Originally Posted by RWO View Post
    Actually, the reverse is true. 22LR has a max pressure of about 24.5K psi. 3" .410 is 13.5K psi. It is important to design for the breech bolt back thrust taking into account the shell head inside area.

    But the forces involved are much greatere with the .410. FOr a discussion the explains some of the issue take a look at He suggests the a blowback semi auto would require about 7 times as much weight in the bolt to absorb the energy of the .410

    A .22 would make a good first choice, .38 or 9mm Parabellum would make a nice second gun. Can purchase barrels for them from Green Mountain Barrel - Search online for barrel liners for various callibers.

  3. #23
    Join Date
    Jun 2011
    Northeast, PA


    I’m a little late to this thread but I have been thinking of doing one of the Serbu gb-22’s. It’s a pretty simple pistol but looks like a fun project. There is some videos of a closed bolt version that ejects shells with no extractor or ejector. I hope a version of those plans come out but it seems like he may be wanting to sell that as a complete firearm.

  4. #24
    Join Date
    May 2008
    central Arkansas


    Quote Originally Posted by H380 View Post
    Smooth bore pistols are an ATF no go for modern firearms. It MUST be a rifled barrel.
    In most cases. But there are the "short barreled shotgun" and "any other weapon" categories, which are still legal, though an expensive hassle.

    Also the rifled barrel bore can be no larger than 50 cal without ATF "Sporting purpose" approval.
    If ATF has ever denied an application for a >.50 caliber exemption, the applicant has been quiet about it. The guys over at have never had any denials no matter what absurd monsters they've built.

    The exemption goes for the cartridge design, not a specific firearm. If you got approved for the "H380 .888 Magnum", anyone else using the same cartridge is also exempt without having to deal with the ATF.

    There's also the "rifled shotgun" category, which is special. The ATF's rulings are essentially "once a shotgun, always a shotgun" no matter what barrel or caliber. (frankly, I'm not sure what the deal is with the guys who convert old Purdey or Greener shotguns into rifles; many of them are too new for the pre-1898 rule) and "if it will still physically chamber a shotgun shell, it's still a shotgun and the .50 limit does not apply." (the latter ruling specifically for the 12gaFH and its derivatives)

    Which is why 45LC/.410 are the standard.
    That's another special case for the ATF. Since many .410 shells (there's a lot of size variation between brands) will drop right into a .45LC chamber, and a couple of manufacturers took them to court over their initial ".45 LC pistols are illegal short shotguns" ruling, the latest ruling is that guns chambered in .45LC are *not* shotguns, which would be obvious to anyone, but that's politics, not gunsmithing...

    You can not just scratch a smooth bore and call it rifling. The ATF has it defined somewhere.
    That question comes up every now and then. If the ATF has a spec they hide it well. It would seem logical that they would; perhaps they simply haven't had cause to make a ruling on it yet.

    Bear in mind that most rifling is only .001-.002" deep to start with, and a century or two or shooting and cleaning can polish a bore smooth. Some old guns, you can only tell they were once rifled if you shine a light down the bore just right... and some modern guns don't even *have* rifling per se. That'd be your "polygonal bore" pistols, largely. And then you have things like "paradox" rifling. And I have some .44 caliber adapters for my 12 gauge; they have about 1-1/2" of rifling, but whether the insert or the gun counts as a barrel isn't defined anywhere in ATF regs either. Writing regulations to adequately cover all the edge cases would be... interesting.

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