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Old June 26, 2013, 07:17 AM   #26
Bill Akins
Senior Member
Join Date: August 28, 2007
Location: Hudson, Florida
Posts: 1,030
I understand most of what you are saying Captchee, but there's two things I don't understand. When you said: "Also , even though there will be some back pressure applied to the rear projectile , any real force would I believe serve to possibly enlarge that projectile."

Do you mean the front gas pressure might deform the rear ball to where the rear ball having pressure against it from the front gas, would push the rear ball backward against its charge and possibly push and deform the rear ball tighter against the walls of the chamber, and thus make the rear ball have a tighter seal against the chamber walls that might help to stop the front gas from getting past it to set off the rear charge? Is that what you meant?

I don't see that happening for the same reason you mentioned about pressure seeking the path of least resistance. It would be less resistance for the front gas to squeeze past the rear ball (and into the rear charge) than it would be for the front gas to force the rear ball tighter to the cylinder's walls.

That also brings up the question of what effect that would have if the front gas pushed the rear ball rearward, thus heavily compressing the rear charge's powder charge? Would the rear powder charge being heavily compressed have any adverse effect?

My other question is, on that double barrel flintlock pic you showed, that seems like it isn't the same thing I was describing. Because the flash channel of one barrel is rotated away from, and closed off from the priming powder. And since the flash in the flintlock's pan is open to the air and not contained, I can understand how that rotating pan would be sufficient to keep the other flash channel away from sparks since the other flash channel in the pan is completely rotated out of the way of the pan's spark, and there is no contained pressure that could force the spark around the rotating pan and into the other flash channel.

But that isn't the same thing as superimposed charges on top of each other. Because then the hot gases and sparks are more contained (than in an open to the air pan) and pressurized and could under pressure squeeze past the rear ball and wad and into the rear charge.

Hawg's mention of the barrel to cylinder gap allowing bleed off of any overpressure could lessen the overpressure, but the questions are, is it enough bleedoff of overpressure to prevent a bulged barrel or to keep the cylinder and or barrel from exploding? And would the front ball be out of the cylinder and into the barrel before any overpressure occurred? Or would the overpressure occur so fast that the ball would not have left the cylinder before too high of overpressure occurred?

I think the only way to tell would be in a lab where the cylinder was drilled to allow high pressure sensor tube fittings to be screwed into it in both areas of high pressure that I mentioned in my sketch, that was hooked to two pressure gauges, to measure what the pressure was in both those areas (using different grain charges) if both charges went off and before the front ball entered the barrel. To see exactly what degree of pressurization was occurring before the front ball went into the barrel and thus passed the barrel to cylinder gap to allow that gap to bleed off some overpressure. In addition to that test, another test could be done without a barrel attached to the cylinder and in conjunction with the two sensor tubes and gauges, also perhaps using high speed photography to see if the front ball had left the cylinder before high pressure built up.

Such a test as that might lead to making a larger cylinder (or smaller caliber holes in the cylinder) so that there was more metal between each chamber if necessary to make it stronger so it could safely hold overpressure (depending on the degree of overpressure the sensors and gauges read). And also perhaps a thicker barrel. To allow enough metal in the barrel thickness and between the chambers to take whatever overpressure was measured, to make it safe for the pressures involved.

Although they had high pressure steam gauges back in the 1850's, the kind of instantaneous high pressure tube sensors and gauges I am thinking about might not have been available back then for them to test the Walsh revolver. Or if they were, perhaps they just didn't think to use them to test with. In Matthew Brady's day, I doubt if high speed photography was even invented yet. So even if they had a way to test two areas of pressure within a cylinder and barrel, they might not have been able to test what the pressures were before the front ball had left the chamber of the cylinder.

It would be great if the Walsh design could be tested and proven safe today and reproduced. Until such tests were undertaken and proven safe, I'd remain skeptical of its safety due to possible overpressure.

All academic questions, but good things to think about and discuss.

"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; June 26, 2013 at 08:10 AM.
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