black powder .45 ACP pressure data?

Atlantic_shootist

Atlantic_shootist

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I've been reloading 9mm and .45ACP for some time now and also hunt with a TC .50 muzzle loader. As an experiment I'm considering working up a load for my G21SF with hodgden tripple seven in FFFG.

The powder manufacturer website specifically states that FFg is allowed for cartridge reloading __NOT__ FFFg. After spending several hours scouring the internet I've determined that this prohibition was made due to liability concerns over antique firearms that are weakly constructed or in poor condition. Their worry would seem to be that the increased burn rate due to the increased surface area, and charge weight per unit volume, would overpressure vintage black powder guns.

I've read a number of articles authored by Wakefield that contained PSI/CUP data but they were all about muzzle loading rifles. Rough calculations would seem to indicate that the expected peak and sustained pressures would be reasonable, but I'm looking for more specific information. Given that the modern firearm in question is made with low-impurity, properly heat treated steel is vastly more robust than antique BP firearms I've little concerns regarding safety but that being said I'm sill cautious and was hoping someone reading this message might know of, or have access to 777 FFFg pressure data in pistol loadings, cartridge or not.

Any data regarding this matter you'd be willing to share would be greatly appreciated.
 
My Lyman Black Powder Handbook has lots of ffG and fffG loads for cartridges. There all for old original BP calibres though.

I would hazzard that any .45ACP gun that can fire normal ammo will have no problems with safely firing a .45ACP properly loaded with black powder other than you will now have to clean the BP fouling from the gun. You cannot really put too much BP in a case. You must make sure it is packed snug against the bullet or if a lower charge that a wad is used to take up the air space. You do NOT load black powder loosely like smokeless is in many loads.
 
The .45 cal pistol rounds do not list pressure, but 44 Special 240gr lead bullet with 24gr fffG Goex at 883FPS is 13,300 C.U.P.

I do not believe you will create more pressure with proper compressed ffG or fffG BP loads than a book smokeless load.
 
You must load by volume and not weight - fill the case to a level sufficient to obtain about 1/8" compression when the bullet is seated. You will not generate any excess pressure with this method.

Ensure that you do not use plastic measures or drop tubes as they can produce static in conjunction with BP and cause much excitement should combustion result...
 
hk33ka1,

A full-length re-sized .45ACP case loaded with an AIM 230gr FMJ RN at 1.200" COAL has 0.93 cubic centimetres of volume for powder that will accept approximately 11.5gr (weight) of FFFg Tripple Seven with no airspace and very slight (read: almost none) compression. A quick comparison of the .44SPL and .45ACP cartridges shows the pressure in my experiment shall be significantly less than the figure quoted from the Lyman BP manual. I'll play around with these figures and try to estimate the actual pressures in my experiment.

Thank-you very much for your help.
 
I don't think you will find specific pressure data for any modern cartridge (45ACP, 308WIN, 300WSM etc) that was developed and used with smokeless powder since the ammo and reloading companies who have the tools did not likely bother to test them with Black Powder.
 
mudgunner49,

Do you have black powder CUP or PSI data for any other straight-walled cartridges similar in size to .45 ACP such as .45 Short Colt, et al.?

Any constructive data would be greatly appreciated.

Thanks in advance.
 
Ok, I don't know a lot about loading black powder so I may be wrong here, but since the .45 ACP was designed to duplicate the old .45 Colt ballistics with smokeless powder, wouldn't you have to go back to a case with the same capacity as the .45 Colt to get the same velocity? Sort of re-inventing the wheel here aren't we?
 
Further research has narrowed the data envelope. The .45 Schofield case dimensions are a very close approximation to the actual case in question: 1.100" long, 0.060" rim thickness, inside diameter approximately 0.452". On another forum a knowledgeable black powder re-loader posted the following data from a Hodgdon 2007 manual:

.45 S&W (a.k.a. .45 Schofiled or .45 M1877)
230gr LRN
25gr(vol) 777 FFg
800fps
6500 CUP

250gr LRNFP
25gr(vol) 777 FFg
813fps
7500 CUP

On yet another forum another poster showed this cartridge has approximately 1.9cc of volume for powder under the bullet with a COAL 1.430" although the bullet weight was not clear it was probably one of the two previously listed weights.
 
I don't know much about the 45 ACP with black, other than to know it would be safe but a few years ago I played with pyrodex in a 300 WSM. Launched 180 gr bullets at about 1800 FPS if I recall correctly, and was decently accurate to boot.
 
Be aware that 777 and other BP substitutes may burn differently than real BP when compressed. I've never used any of them much and don't know the particulars.

Use the real stuff and you can't really go wrong in any gun thats reasonably sound as long as there isn't any airspace in the cartridge.
 
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