1851 .44 brass conversion question

[webrx]

HI all,

I know that it is not recommended to convert an 1851 brass frame to a .45 long colt.

My question is though, if you had shortened the barrel, to avenging angel snub nose lengths (3 inches), wouldn't the pressures be low enough to make this a viable option?

I basically had a brass framed 1851 hanging around that wasn't being shot and decided to chop it. Took the barrel to 3.25 inches, faced an crowned it, and am going to shoot it next weekend but I started thinking that with this configuration I may be able to buy a conversion cylinder and shoot .45 long colts (cowboy loads of course) out of this gun like I do my 1858s.

Any experts care to chime in on whether the shortening of the barrel might offset the general weakness concern of a brass framed revolver?

Thanks

Dave

 

[Crawdad1]

You already have THE experts, the manufacturers, telling you NOT to do it.

 

[webrx]

Thanks for the response Crawdad,

to me, if you shorten a barrel you reduce velocity because you reduce the time the bullet is in the barrel and the time the powder has to build pressure.

So, If you reduce the pressure that can build, is this not similar to reducing the powder load? I.E. 30 grains to 25 grains or 25 to 20, etc.

I understand the manufacture says don't load 30 grains in a brass frame with a 7.5 in barrel, but 20-25 is ok. They also say dont use a conversion cylinder on a BP revolver due to the brass frame being not able to take the pressure.

so maybe what my question really is...

How much does the shortening of the barrel reduce the pressure that is built up, and is this enough to be equivalent to say reducing the conversion cylinder pressure to a similar amount of pressure as say 20 or 25 grains of black powder?

d

 

[Crawdad1]

Webrx, I'm searching my library to see if I can come up with these pressure numbers that you'll need, but I can't find anything.

 

[Jim Watson]

to me, if you shorten a barrel you reduce velocity because you reduce the time the bullet is in the barrel and the time the powder has to build pressure.

This is not the case. Barrel length has no effect on chamber pressure.
Some years ago, Speer built a single shot "cylinder" with pressure transducer for a revolver. They found that maximum chamber pressure was reached before the bullet was all the way out of the cylinder.

 

[webrx]

Thanks,

Gunsamerica shows some numbers for velocity and ft lbs force with 40 grains

3" barrel 685 fps 145 ft lbs energy with 40 grains at the muzzle

7.5" barrel 1214 fps 458 ft lbs energy with 40 grains at the muzzle

Seems to me this is a significant reduction in both speed and pressure

What I don't know is how this translates to pressure in the cylinder on ignition and/or if this reduction in speed and pressure at the muzzle translates to preventing a brass frame from stretching if using cowboy loads in a conversion cylinder.

Not sure I am willing to risk my shooting hand to find out without some more info and remote testing of the theory.

Dave

 

[webrx]

Jim,

Seems we were typing at the same time, and it also seems you may have the answer to the question I was pondering.

Cylinder pressure buildup and muzzle energy / Velocity may not directly translate.

I suspect there is a relationship, but dont know how to do the math to relate them.

 

[webrx]

A little more info on pressure from a cylinder only

The barrel was removed from the 1851 Colt and the gun was fired from the cylinder only. The velocity of a ball discharged from the cylinder was found to have a velocity of 146 ft per sec.

Using the standard Kinetic Energy equation, we may find the energy of the balls.
Ft/Lbs = wv²/450400

Ft/Lbs from cylinder = 148(146)²/450400 = 7 Ft/Lbs

Dave

 

[webrx]

A little more research and it appears that as stated above by Jim Watson barrel length does not affect chamber pressure (internal ballistics)

"for all intents and purposes, barrel length has no real effect on chamber pressure. The chamber pressure is a product of the powder charge weight and the bullet weight more than any other combination of factors. Other things have slight effects (bullet crimp, seating depth, neck diameter, etc.) but those are the two main things that directly effect the pressure"

So, back to square one - No conversion cylinder will be used in my brassie even with a short barrel.

d

 

[rcflint]

The problem is not the pressure of the cartridge load, which is contained in the cylinder, not the frame, but the recoil energy of the much more efficient cartridge, which is like loading a pecussion maximum every time, it will stretch the frame.

 

[shunka]

My Good Webrx -

With all due respect, It appears that you asked the question, having already made up your mind, looking for an affirmation for the answer to which you already arrived .

" Well, you do what you think best, Ned" (J. Wayne, as Rooster Cogburn)

yhs
shunka

 

[BCRider]

Down boys, he's seen the light and reported that he's not going ahead with this back in post #9.

 

[webrx]

Thank you all, yes, I had thought I might do this, I thought it might actually be ok and safe with the shorter barrel, however, through discussion on this thread, and additional research brought on by that discussion I did "See the light" and will not be doing so.

Thanks again

 

[Gaucho Gringo]

Now if you want to shoot .22 the Kirst .22 conversion is ok from a brass frame.

 

[Prairie Dawg]

The bullet slamming into the forcing cone of the barrel puts higher pressure on the arbor (cylinder pin) causing it to loosen up.
If you stick with light loads and light bullets, it most likely won't be a problem.
I know a gunsmith pard who has brass framed guns with conversion cylinders.
He shoots 1 cc (15 grains) of black powder with 165 grain .45 bullet out of them.
Easy on him (he's older) & easy on the gun.

It's the cylinder that takes the pressure from the case.
The brass frame takes recoil against the recoil shield and the arbor.

Just my 2 cents
--Dawg

 

[oldfogey4ever]

It isn't a question of whether the cylinder could take the forces (being's how that's what it was designed for,) it's a question of whether THE FRAME could take it - and the obvious answer is "Probably Not"!