Black Powder Pistol Pressures

[Oyeboten]

Something I have been wanting to know about, are the pressures which are attributed to full-charge, Black Powder Metallic Cartridge Pistol Ammunition.

Or, next best, the pressures attributed to Black Powder Muzzle Loading Pistol Calibers.


I have not found any data on these.


Anyone here have any links or leads or info?

 

[cheatin charlie]

Look for a copy of Lyman's muzzleloading handbook 2nd edition at your library

 

[[email protected]]

I think if I remember 40 years ago right, the 45 Colt was about 9,000 psi.

 

[ClemBert]

SAMMI upper limit is 14K psi (15,900 cup) for 45 Colt.

High Pressure 45 Colt Loads

High Performance 45 Colt Loads

But with 40 grains of GOEX I don't know what is typically acheived.

My Lyman's 2nd addition isn't showing typical pressures for 45 Colt but for other caliber black powder and BP substitute loads for other smaller pistol cartidges it is showing 5K to ~13.5K cup.

 

[Oyeboten]

Thanks ClemBert...


Hmmmmm...


Interesting then...


My not-quite-20-Grain 3F BP, 158 gran Lead Bullet .38 Special rounds, clock faster FPS than off the shelf 'saami' compliant ( I assume, 17,000-18,000 PSI ?) 158 Grain Lead Bullet Ammunition.


Yet...we must assume they do so with around what, 12,000-14,000 PSI?


Interesting...

Very interesting!!


How do dey do it???


Lol...

 

[Pulp]

I don't pretend to be an expert on pressures, but one thing I've found from perusing reloading manuals is certain powders produce higher pressures and lower velocities than others. It has to do with burn rate. BP is slower burning than a lot of smokeless powders and creates a longer peak pressure curve, so it can accelerate a bullet to a higher velocity with less pressure than some smokeless loads. A smokeless load, particularly pistol powders may create a high peak pressure but only hold that pressure for a short time. We're only talking about milliseconds here, I have a hard time grasping how a couple of milleseconds can make all the difference in the world, but it does.

 

[azyogi]

pulp; expert or not, pretender or not GOOD ANSWER

 

[BCRider]

Pulp, if you could see the area under the line on a pressure vs time graph then it may become a lot more apparent.

Let's say for sake of argument that smokeless powder has a peak of 18000 psi and holds that peak for just .5 milliseconds then tapers rapidly off as the bullet transits down the barrel due to the chamber holding the pressure expanding as the bullet causes it to become larger. Now lets say a casing full of black powder burns from the rear forward in a fast but less fast than smokeless way where the pressure builds quickly to 14000 psi but stays above that 14000 for over 1.5 milliseconds before tapering off. The area under the second graph will have a lot more area than the higher but more spike like smokeless curve. Yet there's only a 1 millisecond difference but it's 78% of the push for 3 times as long. So yeah, it'll move the bullet faster with less pressure. But it's the duration of that pressure that makes up for it.

A bullet going from a standstill to 900 fps over a 6 inch barrel has an average velocity of 450 fps. At that average it's only in the barrel for just over 11 milliseconds. But what happens in that 11 milliseconds counts for a lot.

 

[Oyeboten]

Hi Pulp,



Yes...I Believe you have it right.


How disappointing then that the Ammunition Manufacturers do not take a more considered interest in the choice of Powder for Bullet type/weight and application.

'Buffalo Bore' being among the few exceptions I s'pose.


It's fun to brood on interior Ballistics, and to wonder about those 'milliseconds' which in practice, make so much difference.