20mm build

45flaco · November 24, 2022, 09:42 PM

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.

45flaco · November 24, 2022, 09:44 PM

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.

50 shooter · November 25, 2022, 08:42 PM

Have you looked at Anzio Iron Works 20mm?

http://www.anzioironworks.com/MAG-FED-20MM-RIFLE.htm

45flaco · December 7, 2022, 11:25 PM

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.

45flaco · December 7, 2022, 11:30 PM

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

armoredman · December 8, 2022, 06:18 AM

Stumbled on to this, sounds very interesting.

six 4 sure · December 9, 2022, 11:19 AM

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.

50 shooter · December 9, 2022, 09:38 PM

If anything, call Anzio, they might be able to help you out with ideas to point you in the right direction.

45flaco · December 23, 2022, 07:38 PM

Quote:

Originally Posted by six 4 sure

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.

armoredman · December 26, 2022, 01:38 AM

NOE would probably love to make a mold...

45flaco · February 18, 2023, 11:49 PM

I've actually just picked up some bullets locally for about 50 cents each, which really isn't bad.
I do plan to cast some, but I'll just make my own mold.

November 24, 2022, 09:42 PM	#1
45flaco Senior Member Join Date: November 19, 2017 Posts: 134	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.

November 25, 2022, 08:42 PM	#3
50 shooter Senior Member Join Date: August 6, 2002 Location: SoCal PRK Posts: 986	Have you looked at Anzio Iron Works 20mm? http://www.anzioironworks.com/MAG-FED-20MM-RIFLE.htm __________________ I see the world thru bloodshot eyes Streets filled with blood from distant lies The dogs of war never compromise, No time for rearranging.

December 9, 2022, 09:38 PM	#8
50 shooter Senior Member Join Date: August 6, 2002 Location: SoCal PRK Posts: 986	If anything, call Anzio, they might be able to help you out with ideas to point you in the right direction. __________________ I see the world thru bloodshot eyes Streets filled with blood from distant lies The dogs of war never compromise, No time for rearranging.

November 24, 2022, 09:44 PM	#2
45flaco Senior Member Join Date: November 19, 2017 Posts: 134	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.

December 7, 2022, 11:25 PM	#4
45flaco Senior Member Join Date: November 19, 2017 Posts: 134	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.

December 7, 2022, 11:30 PM	#5
45flaco Senior Member Join Date: November 19, 2017 Posts: 134	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

December 8, 2022, 06:18 AM	#6
armoredman Senior Member Join Date: May 22, 2007 Location: Arizona Posts: 5,299	Stumbled on to this, sounds very interesting.

December 9, 2022, 11:19 AM	#7
six 4 sure Senior Member Join Date: November 18, 1999 Location: Harrisburg, IL Posts: 294	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.

December 26, 2022, 01:38 AM	#10
armoredman Senior Member Join Date: May 22, 2007 Location: Arizona Posts: 5,299	NOE would probably love to make a mold...

February 18, 2023, 11:49 PM	#11
45flaco Senior Member Join Date: November 19, 2017 Posts: 134	I've actually just picked up some bullets locally for about 50 cents each, which really isn't bad. I do plan to cast some, but I'll just make my own mold.