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Old November 24, 2022, 09:42 PM   #1
45flaco
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20mm build

Since apparently the 500 Jeffery was much less of a challenge to build than I thought, and EForms has been running well recently, I grabbed some 20mm parts and will be doing the world's dumbest home-built DDs.

Have an old Colt M12 parts kit, a full sized vulcan barrel, and a 16" barrel stub.

The remill on the old colt will be decently easy. Not expecting any issues with that, I've got the semi conversion figured out on paper, and the rest is just welding/machining. Making a magazine will be fun but not impossible.

It's the second gun that I'll have issues with. I plan to make a stubby truck rifle just for giggles. 16" barrel means I can throw a stock on it.
Plan to make it look like the Noreen ULR but with Downs syndrome.
My issue is there is zero information on bolt design, and just using shear calculations, and some messing around, it looks like I'm just going to make the receiver and bolt as a very large mosin.

If anyone has built a 20mm single shot/non-auto 20mm, advice would be super appreciated.
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Old November 24, 2022, 09:44 PM   #2
45flaco
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The part I'm most excited about on the MK12 is that it will be chambered for normal 20x102 Vulcan, not the navy's moronic 20x110 USN stopgap cartridge (which is the reason these kits are almost free).
The vulcan barrel isn't wide enough at the breech to thread directly for the receiver.
So i'll need to make a sleeve for it.
Recoil and gas system will also need tuned.
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Old November 25, 2022, 08:42 PM   #3
50 shooter
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Have you looked at Anzio Iron Works 20mm?

http://www.anzioironworks.com/MAG-FED-20MM-RIFLE.htm
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Old December 7, 2022, 11:25 PM   #4
45flaco
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I have seen it, but I enjoy building things. Gives me something to do other than drink.
It's been quite some time since I bought a gun that wasn't demilled or broken lol.
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Old December 7, 2022, 11:30 PM   #5
45flaco
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I'm kinda stuck in limbo right now, my Form 1 is still "pending research" unfortunately.
So I can make drawings, plan things out, but can't start welding yet.
I did 3d print the bolt and barrel extension at 1/4 scale just to see if my idea works, and it looks like it does
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Old December 8, 2022, 06:18 AM   #6
armoredman
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Stumbled on to this, sounds very interesting.
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Old December 9, 2022, 11:19 AM   #7
six 4 sure
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Are you planning to roll your own or purchase ammo for this beast? I ask because I might be able to point you to some "scrap" brass and bullets.

I used to work at a DOD plant that loaded 20mm. I ran, and later, inspected the 20 prime machine. I think they sold all our scrap to a local company.
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Old December 9, 2022, 09:38 PM   #8
50 shooter
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If anything, call Anzio, they might be able to help you out with ideas to point you in the right direction.
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Old December 23, 2022, 07:38 PM   #9
45flaco
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Quote:
Originally Posted by six 4 sure View Post
Are you planning to roll your own or purchase ammo for this beast? I ask because I might be able to point you to some "scrap" brass and bullets.

I used to work at a DOD plant that loaded 20mm. I ran, and later, inspected the 20 prime machine. I think they sold all our scrap to a local company.
I am planning to reload my own. I'd very much appreciate any leads on components, as right now I'm looking at upwards of 10 dollars a round with the current batch of components I've got.
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Old December 26, 2022, 01:38 AM   #10
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NOE would probably love to make a mold...
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