Cartridge/ml pressure question

[elhombreconnonombre]

I was wondering what kind of pressures might be generated by a black powder .45 Colt cartridge conversion and the stresses generated on the frame as opposed to an equivalent weight/bp ball and powder charge in a non converted "ml" revolver?

 

[rcmodel]

That's a hard question this late at night.

A .454" lead ball weighs 141 grains, and can be driven about 1,100 FPS with black powder.

A .454" .45 Colt bullet weighs 255 grains, and is driven about 900 FPS in the old black powder load.

So, the ball develops about 358 ft/lb energy.
The bullet develops about 458 ft/lb energy.

So, without a degree in rocket science?

I would say a full power .45 Colt cartridge would hit the frame with about 100 ft/lb more force.

But, most people don't use full power .45 Colt in conversions.

So realistically, they are probably both about the same.

rc

 

[Don McDowell]

The Lyman Blackpowder handbook will tell you that the 44 cap and ball revolvers generate around 8500 cup, and that the 45 colt will generate up to about 14000 cup, so yes the cartridge conversion will be putting more stress on the gun.
The cost of those convertion cylinders would seem to make it a much more cost affective thing to just buy a 45 colt handgun ?

 

[Old Fuff]

As an aside:

It is my understanding that Italian cap & ball revolvers have investment cast frames, where similar revolvers made originally to use metallic cartridges have forged frames - this reflecting that the latter are proofed to use smokeless powder - and I presume heavy charges of black.

 

[Slamfire]

The Lyman Blackpowder handbook will tell you that the 44 cap and ball revolvers generate around 8500 cup, and that the 45 colt will generate up to about 14000 cup, so yes the cartridge conversion will be putting more stress on the gun.

I had a Lyman Blackpowder handbook and I thought the pressures were Lead Crusher units not Copper Crusher Units. I don't remember a conversion between the two.

Black powder guns have very low quality steels that are often not even heat treated. This is due to the low pressure of black powder. I have seen those conversation cylinders for black powder revolvers, and while I expect the cylinder is of decent heat treated steels, I would be very concerned whether the pistol frame can hold up to the pressures of smokeless. I would not be concerned if the cartridge used blackpowder, but, I don't know that much about blackpowder pressure curves.

 

[Don McDowell]

As long as the smokeless loads were held to the saami spec the pressure would not be much different from the blackpowder loads.

 

[TruthTellers]

The conversion cylinders are bulletproof as long as you keep the pressures below 14000 PSI. I'm pretty sure they are proofed to standard pressure .45 Colt to ensure they don't blow in case somebody mistakenly shoots a modern .45 Colt.

The thing that was stressed to me when I called the manufacturer about that advertised "below 850 fps" threshold was to NOT use jacketed bullets. The frames are built to swage lead, not copper. With lead bullets, I was told you can push the fps up to 1000 and it's safe to shoot... and that's with smokeless.

Personally, I would not use any smokeless loaded lead bullets that go over 900 fps. I also would not use anything hard cast for everyday shooting. At speeds less than 900 fps, you don't need hardcast anyway.

To better answer this specific question, I would look back to what loads were being used in converted percussion revolvers. .45 Colt wasn't the predominant cartridge in these guns, there was .46 Rimfire, .44 Henry, .44-40, etc. The .44-40 was using, obviously, 40 grains of bp to push a 200 grain bullet, so I would suggest not shooting more than a 200 grain bullet when you want to shoot full power bp cartridges.

I think you could get away with shooting a 250 grain bullet with a max load of black powder, just not everyday.

 

[rcflint]

The conversion cylinders by Howell/Tatlors or Kirst will take SAAMI loads. The frames are strong enough to take the recoil, though softer than the cartridge frames like the 71 Opentop and SAA, and factory Remington conversions, they will survive. The steel is a quantum leap over the original 19th Century metal, even though it is not the steel used for the cartridge frames. Just don't use brass framed guns. I used Navy Uberti 51 Colts with smokeless 38 loads, and Pietta Remingtons with conversion cylinders in smokeless 45Colt as main match guns for years in CAS.

 

[TruthTellers]

rcflint, what was the average fps of the ammo you were shooting in the Navy and the Remington? And what were the bullet weights?

 

[45 Dragoon]

RC is right. Some folks just need something to worry about. The sammi specs are 1400 or less. 1000 fps 255 gr. Is perfectly fine. Hard lead won't lead the barrel like soft will ( so do which ever you like).
These questions keep coming up and the answer is 1000 fps (kirst) . That said, someone all ways warns to shoot cowboy only or I wouldnt shoot anything over 900. I've never shot anything but factory equivalent loads (not cowboy factory!) and never any black powder loads (can't where I shoot). Wouldn't if I could anyway, I've cleaned all the BP I care to.

The main thing is have fun, don't shoot "magnums " and you're good to go!! Tell us how much fun your having instead of what you wouldn't shoot!!

Mike
www.goonsgunworks.com

 

[dickydalton]

Velocity(FPS) is measured after the bullet leaves the barrel. I'm pretty sure there is a difference in velocity from identical loads shot from guns with different barrel lengths too.

 

[yugorpk]

When I first got a 45 colt conversion for my 1858 pietta I ran a few cylinders of triple 7 in 45 colt cartridges. 40 grains with a 255 grain bullet and were difficult to get that much powder in there. Those were coming out the barrel in the low 1200 fps range. Felt awfully stout. Then I read that I shouldnt be doing that so I keep them to around 1000 FPS now with 8.5 grains of unique. No harm to any of the guns components though.

My Ruger Old Army's get fed a steady diet of max triple 7 loads and I don't think twice about running standard jacketed 45 ACP factory loads through the Kirst conversions.

 

[45 Dragoon]

Yugorpk,
And you shouldn't!! (Worry)

Mike
www.goonsgunworks.com