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Is this rifle theoretically possible?--a big bore, semi-auto, rimfire

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Is this rifle theoretically possible?--a big bore, semi-auto, rimfire

Old 02-21-2018, 05:48 AM
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Typical Buck
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Default Is this rifle theoretically possible?--a big bore, semi-auto, rimfire

Something like this---a rimfire cartridge in a caliber designed to perform more like a round used for bigger game. In other words, a semiautomatic in .223, .308 or some such but the cartridge is actually a rimfire?

I'm speculating on this in connection with gun debates about banning AR-15s and so forth. A lot of people are looking at these as categorically different firearms, and that is not the case at all. As I was poking around, I learned Gatling guns fired a cartridge called the .58 Gatling, which I understand was a rimfire round (I presume blackpowder).

It got me wondering if it's theoretically possible to build a modern sporting rifle around a cartridge like that in a smokeless rimfire. My amateur's sense is that it would be.
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Old 02-21-2018, 07:10 AM
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I am sure you could build the rifle, however making a cartridge that has the fulminate of mercury in the rim of the cartridge without specialized and expensive tools would be the problem. There was also a rim fire .58 Miller cartridge besides the Gatling and even the Winchester Yellow Boy used rim fire ammo if I am not mistaken.
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Old 02-21-2018, 11:17 AM
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Typical Buck
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Thanks, Oldtimr. It would not be practical by any means, I agree. I think the concept shows how firearms differences are fuzzy and hard to pin down.


BTW, I looked up the Henry rifle and it says the cartridge was called .44 rimfire or .44 Henry.
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Old 02-23-2018, 06:51 AM
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I believe the main issue with rimfires is pressure. It has to be a thin enough rim so the firing pin can crush the case and low enough pressure so that it doesn't blow out the case.

There were quite a few black powder rimfires historically.

-Jake
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Old 02-26-2018, 11:01 AM
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It has to be a thin enough rim so the firing pin can crush the case and low enough pressure so that it doesn't blow out the case.

That's a good point. That might be a technological barrier.

Thanks for the input
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Old 02-26-2018, 12:23 PM
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didn't someone recently make a safe 22mag semi auto? maybe CZ etc...?


not a rimfire, but browning BAR comes in a .338 win.mag.
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Old 03-02-2018, 09:14 AM
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Savage had one... A22 they called it. I never handled one.


-Jake
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Old 03-02-2018, 10:22 PM
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There are unimpressive, by modern standards, cartridges which are loaded to sufficiently low pressures such they would work with a rimfire case head, safely. 45-70 being an example. I personally wouldn't care to have a semiauto bolt slamming a rimfire 45-70 into my chamber, and I'd have to see a lot of research data to show me a 400grn slug loaded cartridge couldn't be dropped on the rim and made to fire (this is very difficult if not impossible with centerfires, due to the necessity of crush velocity against the anvil, and the otherwise protected nature of the primer itself). Keeping the larger diameter, broader rim in good shape for cycling would be less than fun to design as well.

Look at the lengths Franklin had to go to, to get the 17WSM to run right. At a paltry 25grn and 33,000psi...

And of course - rimmed cartridges feed in semiautos like kidney stones. Less than pleasant in anything larger than 22LR, and requiring a swept angle magazine.

A guy just isn't going to get to 223 or 308 win pressures in a rimfire case, safely. At least not with any reasonable cocking force and trigger pull. Punctures and ruptures would be far too great of risk for me to ever lay my face down on the stock of a 60,000psi rimfire cartridge. Consider what the increased area of a larger diameter cartridge means as well - not just greater pressure, but far greater net force as well, pressure times area = force, pressure would be greater, area would be greater (double diameter = 4x area), so doubling the pressure and doubling the diameter to something like 44mag would take the gross force up by 8x!!! All contained by a wimpy rimfire case head. Nothing I want near my eyeballs...

It's not so different, in design, than the old balloon head 45 colt case. And those worked so well with increasing pressures...

The day you design around the law, the next the law will change. Spend your efforts communicating with your elected representation to protect the rights you currently have, rather than focusing energy into a temporary means to skirt a specific phrasing used in law.

Last edited by Nomercy448; 03-02-2018 at 10:25 PM.
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Old 03-11-2018, 05:09 AM
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H&R made 22WMR semi's for years
RR
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