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Old September 11, 2011, 10:04 PM   #75
Bill Akins
Senior Member
 
Join Date: August 28, 2007
Location: Hudson, Florida
Posts: 1,031
Quote:
Stephanie B wrote:
Yes, but you're not talking about a delayed blowback or short recoil action. You're mulling over a gas piston. Isn't it going to depend on how much gas you allow into the piston's expansion chamber?

For instance, I have an adjustable gas port on my Garand. I can set that between "all of the gas into the expansion chamber works the operating rod" to "it all gets vented out and the operating rod doesn't budge".

You've got the mass of the arbor/piston, the mass of the hammer, the rotational mass of the cylinder and the resistance of the mainspring, all working against the gas coming into the piston. The key would be to just admit a little bit, just enough to move the hammer back to full cock.
I once owned a semi-auto .44 Ruger carbine that had an adjustable gas port so that I could increase or decrease the amount of gas. I also have an M1A that like your Garand, has a gas cutoff, but that just cuts off the gas completely rather than gives different setting where it can be decreased or increased.

But what concerns me is that even if I made a gas cylinder adjustable, by decreasing the gas, it still might be too violent and abrupt a movement against the parts even if it didn't have enough force on a decreased setting to actually cock the hammer all the way. It's not the amount of gas pressure I'm as worried about, as it is the speed at which the parts will operate under gas pressure. Even under lowered gas pressure. Even if I was able to carefully dial in the exact precise amount of gas just barely necessary to
cock the hammer, I fear it would still be too violent and abrupt a movement on the parts.
That's why I'm trying to figure a way to slow down the movement of those parts.

But you still could be right Stephanie that all I need is to decrease the gas pressure and if I was lucky, the parts might work okay even with the less amount of gas operating them at a high speed. The only way to find that out would be to experiment.

Quote:
Stephanie B wrote:
Downside is that once you figure out how to do all that, you're kind of limited to one level of power for your loads, as increasing power would slam the beejeez out of the gun and decreasing power would mean the hammer didn't go all the way back. Not sure where you could install a coil spring to slow down the piston if you wanted to.
The amount of gas allowed into the gas cylinder could be made adjustable like on my old Ruger .44 semi-auto carbine was. Then I could vary my powder loads and still dial in the amount of gas I needed for the system to work. Finding a place to install a coil spring to rebound the piston or resist its rearward movement won't be a problem. But I like how you think Stephanie.
It's hard to find many guys who understand this stuff. Even rarer to find a woman who does. I didn't mean that to sound condescending, but as a compliment.

Quote:
Stephanie B wrote:Nice mental exercise, but maybe there is a reason why self-cocking revolvers haven't been practical.
There could be other reasons Stephanie. The Webley Fosbery semi-auto revolver was both practical and successful. The Mateba semi-auto revolver is another one. I think that's it's not that self cocking revolvers aren't practical, but that only several models have ever been manufactured. I believe that's because "people buy what builders build, and builders build what people buy". And people buy what they are used to and resist change and new systems.

Back in the days of the very first BP revolvers, they were manually cocked.
Then when those revolvers became cartridge loaders, they were still manually cocked (until the Webley Fosbery). So for many generations now people have been used to (and buying) manually cocking revolvers. Then the Webley Fosbery comes out that no one is familiar with and although the RAC issued it to their pilots in WW1, it never really caught on with the general public. Chiefly I believe because people resist change and anything they are not used to. People were used to manually cocked revolvers, just as we are only used to manually cocked muzzleloading revolvers today. It's all we've ever known.

Now today that muzzleloading revolvers are obsolete, most people chiefly shoot them to enjoy the history and engaging in something from the past. Hence the activity in reenactments and Cowboy action shooting. Not too many people are interested in finding a way to make an obsolete muzzleloading revolver work semi-automatically. It wasn't done back then, so they may think why bother doing it now since it's obsolete.

But I think it would be cool to have a semi-auto muzzleloading revolver. It would be an interesting piece of machinery. And now is the time to do it since today we have less fouling black powder substitutes that would enable things like gas pistons on them to operate without fouling up.

I'm just searching and trying to figure out what would be the best system design to use. A zig zag cylinder with elongated firing pin tappet that the zig zag friction system would delay the movement of? Or using drilled out nipples for direct cap/gas blowback against the hammer? Or using a gas piston? All while trying to figure out how those systems would affect the speed, wear and breakage of parts. It's a mechanical thing and I know it can be done. Just trying to figure out what is the best method to use. I can't be cutting up multiple '58 Remys trying to find that out, so I have to figure out the best way to go before experimenting.

Here's another interesting concept that a friend of mine named Akumabito from the Netherlands that also belongs to the Brass Goggles steampunk forum posted, that uses and expands more on the other member Otto's arbor pin/gas piston concept that I posted earlier here. Akumabito proposes I use the frame area as a gas cylinder while using Otto's basic arbor pin/gas piston.
Not a bad idea. It could work but would require drilling up though the bottom of the frame into the barrel, then plugging the frame where I had to drill through what would become the gas cylinder. His gas port is WAY to large but this is just his concept rendering.

Also the lugs of his arbor pin/piston would have to be removed and the arbor pin/piston shortened considerable. Plus he shows the frame hole for the arbor pin being factory closed in its front when it is not. So that open end would have to be threaded and plugged hence the need to remove the arbor pin lugs. The advantage of this concept would be that the rammer could still be used and outwardly for the most part, there would be no indication that the revolver was semi-auto or had been modified. To remove the cylinder the plug would have to be removed from the front of the gas cylinder and the arbor pin/piston pushed from the rear so it came out the front in order to remove the cylinder. Actually a great discrete looking concept if delaying the speed of the operation isn't necessary. Except for the missing arbor pin lugs people would hardly notice anything different just looking at it.



Then here's my concerns I wrote back to him on his rendering at Brass Goggles steampunk forum.....



I also wrote my concerns on Otto's earlier rendering too at Brass Goggles.
Otto's concept is good too and he was the first one to theorize using the arbor pin as a gas operated piston. Only his concept hangs a gas cylinder on the barrel which would cause a trimming of the rammer to make the rammer so thin, as to be unable to be used. I added the rough frame outline in yellow and the red text and arrow to Otto's rendering....



In response to my concerns, Akumabito proposed his rendering of this.....



I haven't had a chance to analyze that "AK" '58 Remy concept of his adequately yet. I did notice he extended the hammer up for the piston to push against. According to him, no mods to the rest of the revolver, no gas hole to drill and nothing in the way of the rammer. Has possibilities, but gosh, I still can't make up my mind if it's cool looking or ugly .

I'm also a little worried about using the gas piston in either Otto's or Akumibito's renderings. Imagine if the part of the gas piston that keeps it from coming out the rear broke and it somehow deflected and got past your cocked hammer. Zing! Right into your face or eye. That's why I still like my idea for utilizing the zig zag cylinder of the Webley Fosbery system. Plus that one has a delay for the operation built in.

Continuing to research.

Thoughts?


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__________________
"This is my Remy and this is my Colt. Remy loads easy and topstrap strong, Colt balances better and never feels wrong. A repro black powder revolver gun, they smoke and shoot lead and give me much fun. I can't figure out which one I like better, they're both fine revolvers that fit in my leather".
"To be sure of hitting the target, shoot first and call whatever you hit the target".

Last edited by Bill Akins; September 12, 2011 at 06:06 AM.
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