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Posted: 12/13/2016 11:54:41 AM EDT
[#1]
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On a more constructive note, how about a roller delayed locked breach with a recoiling barrel? Basically a CZ-52 action scaled up about 300%. Simple design, and the recoiling barrel will help smooth out some of the recoil. http://www.outdoorebooks.com/ebay/cz52en/im-11.jpg I was basically scaling up an AK like bolt/carrier using 3 lugs and a barrel and barrel extension. Mostly so you could take the thing down as it was going to weigh something like 100lbs and have a 38" barrel. But also because barrel extensions make a lot of the necessary machining operations easier. hispano suiza Still think he ought to do recoil operated. But my wishes have the same weight as everyone else's here - way WAY less than the OP's. |
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Posted: 12/13/2016 12:01:52 PM EDT
[#2]
Holy buttery tittys, I thought the Anzio 20mm rifles were insane, but a semi-auto? Going to be epic!!!
Going to do 20MM Vulcan or 20x138 Solothurn? |
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Posted: 12/13/2016 1:29:44 PM EDT
[#3]
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As I recall driving bands were to provide a soft material that would be engraved by the rifling when the projectile itself might be inappropriate - cast steel for fragmenting, or a thin casing for explosive charge. If the projectile itself is soft material, I'd think they wouldn't be necessary. But, instead of lathe turning solids, what about using tubing? 20mm is 0.787". 2 options:
For a few reasons. I've drawn jackets for smaller calibers, it's a valid proposition, but casting the lead core is problematic. Hard to get consistent weights without swaging the core, inserting it, then swaging the assembly to final diameter. And I have CNC turning equipment at my disposal. Turning out 100 brass or bronze or copper solids would be a higher material cost, but a lower time+material cost for me personally. If shooting it became such an expense that I needed to find a cost reduction in ammunition, then what you're proposing would be my next step. I have a press capable of doing it. I would just need to make dies. |
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Posted: 12/13/2016 4:29:59 PM EDT
[#4]
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For a few reasons. I've drawn jackets for smaller calibers, it's a valid proposition, but casting the lead core is problematic. Hard to get consistent weights without swaging the core, inserting it, then swaging the assembly to final diameter. And I have CNC turning equipment at my disposal. Turning out 100 brass or bronze or copper solids would be a higher material cost, but a lower time+material cost for me personally. If shooting it became such an expense that I needed to find a cost reduction in ammunition, then what you're proposing would be my next step. I have a press capable of doing it. I would just need to make dies. Quote HistoryQuoted:
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As I recall driving bands were to provide a soft material that would be engraved by the rifling when the projectile itself might be inappropriate - cast steel for fragmenting, or a thin casing for explosive charge. If the projectile itself is soft material, I'd think they wouldn't be necessary. But, instead of lathe turning solids, what about using tubing? 20mm is 0.787". 2 options:
For a few reasons. I've drawn jackets for smaller calibers, it's a valid proposition, but casting the lead core is problematic. Hard to get consistent weights without swaging the core, inserting it, then swaging the assembly to final diameter. And I have CNC turning equipment at my disposal. Turning out 100 brass or bronze or copper solids would be a higher material cost, but a lower time+material cost for me personally. If shooting it became such an expense that I needed to find a cost reduction in ammunition, then what you're proposing would be my next step. I have a press capable of doing it. I would just need to make dies. |
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Posted: 12/13/2016 5:24:49 PM EDT
[#5]
I wonder if a .50 bmg empty case would make a good candidate for transforming into a 20mm bullet jacket?
If so, I have a bunch of fired .50 blanks for you... |
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Posted: 12/13/2016 8:19:23 PM EDT
[#6]
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OP is not new to sailing uncharted NFA waters.  I was totally messing with him. I'm psyched to see this beast! |
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Posted: 12/13/2016 8:26:54 PM EDT
[#7]
Becker 20mm cannon.
https://en.wikipedia.org/wiki/Becker_Type_M2_20_mm_cannon Fired a short case 20mm: http://www.kaisersbunker.com/cc/cc22.htm 
It had advance-fire ignition so no locking lugs needed. (Like Solothurn cannon) 
Seems to be open bolt F/A, but it might be a good starting point. |
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Posted: 12/13/2016 9:22:45 PM EDT
[#8]
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Becker 20mm cannon. https://en.wikipedia.org/wiki/Becker_Type_M2_20_mm_cannon Fired a short case 20mm: http://www.kaisersbunker.com/cc/cc22.htm http://www.kaisersbunker.com/cc/cc22.jpg It had advance-fire ignition so no locking lugs needed. (Like Solothurn cannon) http://www.kaisersbunker.com/cc/cc22c.jpg https://images4.sw-cdn.net/product/picture/625x465_14002914_8613814_1471383155.jpg http://www.landships.info/landships/artillery_articles/images/TAK_Becker_3.jpg Seems to be open bolt F/A, but it might be a good starting point. Advanced primer ignition timing on a 20mm round with a few hundred grains of powder makes my ass pucker. Getting the timing right could be an expensive and exciting process of trial and error. |
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Posted: 12/14/2016 3:15:53 AM EDT
[#9]
God bless America and the OP! :-)
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Posted: 12/14/2016 6:17:27 AM EDT
[#10]
OST
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Posted: 12/14/2016 6:54:58 AM EDT
[#11]
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I heard about a guy who built himself an un-papered 30mm rifle that used a GAU-8 barrel and fired A-10 rounds. IIRC there was a blown up gas station when the thing fired in the trunk of a car while being finger-fucked as he showed it to a buddy who ran the gas station. I seem to recall that many years in Leavenworth was the main result from that exercise. Quote HistoryQuoted:
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Shit man, why not go 30mm? You could be the only guy on your block who shoots the same rounds as the the A-10. Heck, maybe there are even GAU-8 barrels floating around out there. I heard about a guy who built himself an un-papered 30mm rifle that used a GAU-8 barrel and fired A-10 rounds. IIRC there was a blown up gas station when the thing fired in the trunk of a car while being finger-fucked as he showed it to a buddy who ran the gas station. I seem to recall that many years in Leavenworth was the main result from that exercise. GAU-8 is as big as a car. Car > trunk. Somethings up here. |
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Posted: 12/14/2016 7:06:31 AM EDT
[#12]
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The only thing I can think of off the top of my head would be a stout 10ga shotgun action. LOL...wouldn't want to even be close to it when the hammer fell. |
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Posted: 12/14/2016 8:15:40 AM EDT
[#13]
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GAU-8 is as big as a car. Car > trunk. Somethings up here. 30mm SBR 
Sounds like a story along the same lines as the police car radar causing a Harrier to lock on and try to fire a Sidewinder at it... |
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Posted: 12/14/2016 8:46:02 AM EDT
[#14]
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I, for one, will sleep better in my bed at night, knowing that a rough man stands ready to do violence on my behalf with a homemade 30mm rifle. You go, OP. He ain't ready to do violence with it, he's ready to recreate and be cultural with it. |
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Posted: 12/14/2016 8:56:01 AM EDT
[#15]
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Since I assume you are prepared to do some machining and modification anyway, what about starting with the receiver design from an older HMG? The old styles of HMG were scaled up to some impressive calibers well above 20mm, and their receivers were effectively welded boxes. Think Maxim-type stuff, or ww2-era autocannon. It might be easier to approach it from that angle, rather than the anti-tank rifle angle. Of course going off of an autocannon lineage is going to bring much more weight, but it might also be significantly easier to build. Looking at something like the 37mm QF 1-pounder Maxim (there is a great Forgotten Weapons video on it showing the internals) might give you ideas. What kind of 20mm are you thinking? There is a world of difference between a custom short 20mm (like a 20mm version of the old stubby 37mm used in the 37mm Maxim) and one of the bigger 20mm rounds like 20x102mm or 20x138mmB. That idea won't be practical, to be a non DD, it needs to be a RIFLE, which requires a shoulder stock. A 20mm firearm would not fall under the exemption. |
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Posted: 12/14/2016 9:07:31 AM EDT
[#16]
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That idea won't be practical, to be a non DD, it needs to be a RIFLE, which requires a shoulder stock. A 20mm firearm would not fall under the exemption. That's part of the reason my design was following the path it was, to be a shoulder fired rifle, just for different reasons. I really just wanted to one up Jerry Miculek's rapid fire with a Barrett on YouTube. . I'm a pretty big boy I think I could do it if I can keep it under 100 lbs.
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Posted: 12/14/2016 9:12:48 AM EDT
[#17]
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Advanced primer ignition timing on a 20mm round with a few hundred grains of powder makes my ass pucker. Getting the timing right could be an expensive and exciting process of trial and error. Quote HistoryQuoted:
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Becker 20mm cannon. https://en.wikipedia.org/wiki/Becker_Type_M2_20_mm_cannon Fired a short case 20mm: http://www.kaisersbunker.com/cc/cc22.htm http://www.kaisersbunker.com/cc/cc22.jpg It had advance-fire ignition so no locking lugs needed. (Like Solothurn cannon) http://www.kaisersbunker.com/cc/cc22c.jpg https://images4.sw-cdn.net/product/picture/625x465_14002914_8613814_1471383155.jpg http://www.landships.info/landships/artillery_articles/images/TAK_Becker_3.jpg Seems to be open bolt F/A, but it might be a good starting point. Advanced primer ignition timing on a 20mm round with a few hundred grains of powder makes my ass pucker. Getting the timing right could be an expensive and exciting process of trial and error. And you're opening a whole different can of worms with an open bolt. |
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Posted: 12/14/2016 9:37:35 AM EDT
[#18]
read up on the twelve gauge from hell (12-gafh)
sporting as all get out |
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Posted: 12/14/2016 10:24:00 AM EDT
[#19]
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read up on the twelve gauge from hell (12-gafh) sporting as all get out That I haven't heard of in a while. I remember when Hugh (I think?) started that project on homegunsmith/Roderus years ago. He got some obscene performance out of that thing. |
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Posted: 12/14/2016 11:07:32 AM EDT
[#20]
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GAU-8 is as big as a car. Car > trunk. Somethings up here. I've thought that every time I've read that in this thread. I don't see a functional 30mm rifle fitting in the trunk of a car. Strikes me as BS . |
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Posted: 12/14/2016 2:12:57 PM EDT
[#21]
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GAU-8 is as big as a car. Car > trunk. Somethings up here. So you're saying that one barrel, that could be cut to any length for the project, is as big as a car? Or are you just using really bad logic? |
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Posted: 12/14/2016 2:29:33 PM EDT
[#22]
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So you're saying that one barrel, that could be cut to any length for the project, is as big as a car? Or are you just using really bad logic? Quote HistoryQuoted:
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GAU-8 is as big as a car. Car > trunk. Somethings up here. So you're saying that one barrel, that could be cut to any length for the project, is as big as a car? Or are you just using really bad logic? Even cut down a 30mm rifle is probably going to be huge. 20 - 30 lbs at the absolute minimum and probably a lot more. Look how big a Barrett is, and you break one down for transport generally. An assembled Barrett isn't going to fit in a lot of trunks, and a 30mm rifle is probably going to be worse. |
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