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unspellable

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With a cap & ball revolver, a ball seated on chamber as full of FFF as possible is usually considered to be a maximum working load. My question is, how do you proof it? The chamber is already full before you get to a proof load. Not like a muzzle loading rifle you can load a double charge of powder and two balls.
 
Ruger proof tested the Old Army with chambers full of Bullseye, but I don't know about any others.

Interesting question.
 
It's not how do I prove it, it's how did they prove it?

A cap lock will not reliably ignite smokeless powder but with a primer charge of 5 or 10 grains of powder and a suitable charge of smokeless one could get some pretty high pressures. But they were proving these things before smokeless was around. All the modern proof loads I've found for non-revolvers used black powder.

That 8,818 psi number I view with a lot of suspicion. I've seen these low numbers on black powder barrels before and they are not realistic. We are missing something about how they are stating pressures. Black powder revolver loads typically run around 15000 to 18000 psi.
 
PS. Running the numbers, a peak pressure of 8818 psi in a 45 caliber barrel six inches long doesn't give anything like the muzzle energy we expect from a six inch 45 caliber black powder pistol or revolver.
 
I'm curious what the 15-18,000 psi loads are equivalent to. What type and strength of powder and with what type of projectile?

Very interesting question BTW.

The only things that would make sense to well overload it would be to use a much finer powder with a heavy wide bearing surface projectile to create much higher pressures.
 
unspellable said:
It's not how do I prove it, it's how did they prove it?

A cap lock will not reliably ignite smokeless powder but with a primer charge of 5 or 10 grains of powder and a suitable charge of smokeless one could get some pretty high pressures. But they were proving these things before smokeless was around. All the modern proof loads I've found for non-revolvers used black powder.

That 8,818 psi number I view with a lot of suspicion. I've seen these low numbers on black powder barrels before and they are not realistic. We are missing something about how they are stating pressures. Black powder revolver loads typically run around 15000 to 18000 psi.
Click to expand...

That's a lot of chamber pressure, 15,000 to 18,000. How are you working back from muzzle energy to chamber pressure? That can't be done. Where are you getting your numbers?
 
It’s true that you cannot determine muzzle energy from the peak pressure and you will note that I have quoted no numbers above. However, it’s very easy to calculate a theoretical maximum muzzle energy keeping in mind that the real muzzle energy will be much less.

The maximum possible energy is simply the pressure times the base area of the bullet times the length of travel in the barrel. This neglects a lot of complications.

It’s not hard to do a back of the envelope calculation that at least tells us whether we are in the football stadium or the baseball park.

The actual energy expended by the powder charge on the bullet will be the integral of the pressure across the length of travel times the area. Without getting into long winded calculus lessons, suffice it to say that the integral is never more than half the peak pressure in a barrel more than four inches long.

Then we must subtract from that energy the loss due to swaging the bullet and friction, which is far from negligible.

Real world pressure measurements in revolvers with black powder loads all run above 8800 psi unless you are talking some really wimpy loads.

In the mean time I did a bit of internet surfing and came across a comment from Pedersoli about proofing. They did not go into methods but did list some pressures. The working pressures were all well above 8800 psi and the proof pressures were 30% above the working pressures.

It dawned on me that I don’t see pressures marked on Italian guns, only the Spanish ones.

So we are still left with two questions, the first one, “How do they proof a cap and ball revolver?” and the second one, “What do the Spanish pressure markings actually mean?” as they seem impossibly low.
 
People! We have an answer to the first question. I managed to track down the CIP proof loads for cap and ball revolvers. First, they specify the black powder used. This powder is not significantly different from any other black powder, just very tightly specified. They use a heavy bullet with as much powder under it as the chamber will hold. For a 44 or 45 caliber revolver, the bullet weighs 231.5 grains. Such a load might happen in use with conicals, so it’s probably not the 30% over working pressure that a single barreled rifle would be proofed with.

It might be worth noting that CIP also has specifications for the steels used and wall thickness.

It remains to figure out what the pressure numbers on Spanish barrels mean.
 
I'd like to know where the "cylinder full of bullseye" story came from. I have seen a Super Black Hawk that was blown up with only 22 grains of bullseye, way less than the ROA cylinder would hold.
Ruger did publish that you could use a full load of ffffg safely, and I have. Well over 1000 fps with round ball.
Proof of old bp guns is an interesting thing. Originals blew up fairly frequently, even the Walkers.
 
I too have seen a Ruger Single Six destroyed by what was thought to be 12 to 18 grains of Bullseye. Automatic powder dispenser was malfunctioning. All other rounds from the loading session were dismantled and loads were from 0 grs to 18 grains.
 
I haven't seen any Rugers blown up but I have seen a S&W Model 10 in 38 Special converted into a hand grenade with what was presumed to be a case full of Bullseye behind a 148 grain wadcutter.

It would be interesting to track down the story about the Old Army full of Bullseye.

A round ball is as light a bullet as you can get. There would be some venting through the nipple. The cylinder walls are a trifle thicker than a 45 Blackhawk. But still .....
 
You guys are cracking me up. You can't compare a cartridge that has a crimp held bullet with a friction held lead bullet in a cyl chamber. Of course you can over load a cartridge case and with the enhanced efficiency of the crimp and smaller effective chamber volume to help with burn rate can blow a cylinder with relative ease.
The ROA has the same materials as the 3 screw blkhwk. The same narrow locking notches that all Ruger S.A.s have. The ROA is by far the strongest C&B rev. ever made. That said, if it can or can't shoot a full chamber of bullseye, it is "by dimension/material" stronger than any C&B revolver from the 1800's.
This is somewhat an interesting question even though I've never wondered how they proof the cylinders. Since the locking notches have plenty of material under them, and as many 60gr. charges I shot out of my '80's kit Walker, I've never been concerned.

Mike
 
PapaG said:
I'd like to know where the "cylinder full of bullseye" story came from. I have seen a Super Black Hawk that was blown up with only 22 grains of bullseye, way less than the ROA cylinder would hold.
Ruger did publish that you could use a full load of ffffg safely, and I have. Well over 1000 fps with round ball.
Proof of old bp guns is an interesting thing. Originals blew up fairly frequently, even the Walkers.
Click to expand...


From "Ruger and His Guns" by R. L. Wilson, Simon and Schuster, 1996; page 126; interview with engineer Harry Sefried:

"The (ROA) was of incredible strength, as Bill always insisted. I decided the logical way to test these was to do so with Bullseye smokeless powder- definitely not recommended to the public! I'd stoke the cylinders up and pop the cap. You can't, however, ignite Bullseye with the spark from a percussion cap going through a tiny hole in a blackpowder cylinder nipple. We opened these up, and boy, were we getting ignition! We found we couldn't get enough Bullseye in to blow the cylinder. Even if not filled up, we could not blow it with Bullseye powder! (Again, not to be tried at home.)"

Someone else will have to speculate what happened with the Super Blackhawk you mention.
 
J-Bar said:
From "Ruger and His Guns" by R. L. Wilson, Simon and Schuster, 1996; page 126; interview with engineer Harry Sefried:

"The (ROA) was of incredible strength, as Bill always insisted. I decided the logical way to test these was to do so with Bullseye smokeless powder- definitely not recommended to the public! I'd stoke the cylinders up and pop the cap. You can't, however, ignite Bullseye with the spark from a percussion cap going through a tiny hole in a blackpowder cylinder nipple. We opened these up, and boy, were we getting ignition! We found we couldn't get enough Bullseye in to blow the cylinder. Even if not filled up, we could not blow it with Bullseye powder! (Again, not to be tried at home.)"

Someone else will have to speculate what happened with the Super Blackhawk you mention.
Click to expand...


Would you mind also quoting the projectile used?
 
In the event that anyone is interested in pursuing a Darwin Award, I will augment it with $100 for the first person who can blow up an unaltered, CIP-Proofed cap & ball revolver using Black Powder of FFFg, or coarser, quality and a projectile that fits the chamber and is less than 12 BHN.
 
Thanks for the info on Bullseye. The blowups, those I've read about, were originals and seemed to be mostly Walkers. Metallurgy was nowhere as good then as now. I shot quite a few 60 grain loads in a repro Walker and aside from the loading lever coming down had no problems. It was fun to stuff my ROA full of 4fg also.
Even if Bill did it, I wouldn't try it myself.
 
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