Should the powder charge be equivalent to the caliber?

[cal.45]

I’ve heard that pistols/revolvers should be loaded with grains equivalent to roundball caliber for optimal performance, like 30 grains for a .30 cal, 45 grains for a .45 cal, etc. Is this true? I’m looking to buy a Philadelphia Derringer in .45, it has a 3” barrel. I’ve never shot a BP pistol with such a short barrel before. Can I load it with 45 grains of powder?

 

[Woody Morgan]

More like half the caliber and work your way up.

wm

 

[nightwolf1974]

I’ve heard that pistols/revolvers should be loaded with grains equivalent to roundball caliber for optimal performance, like 30 grains for a .30 cal, 45 grains for a .45 cal, etc. Is this true? I’m looking to buy a Philadelphia Derringer in .45, it has a 3” barrel. I’ve never shot a BP pistol with such a short barrel before. Can I load it with 45 grains of powder?

I'd look for a Black Powder Loading Manual.....preferably and older one. BUT, I shoot my PA Derringers with only 15grns. of 3F.

 

[Phil Coffins]

Calibre is only one part of the equation, barrel length is to be considered as well. You can fill a three inch barrel to near the muzzle with powder and put a ball in it but will get less performance then a small charge. The powder won’t have a chance to burn but adds to the amount of weight that’s being expelled. So less velocity means less energy. What will the safe load be? Thats another question.

 

[No second place]

You may have noticed BP many pistols and revolvers have longer barrels than their modern counterparts. This was not out of some form of primitive ignorance or just a fad of the old days. Longer barrel length helps increase power and velocity when using BP much more so than smokeless powder. Using more BP than can be burned before the ball leaves the barrel just amounts to more recoil and wasted BP. A A chronograph will tell you the max load or the oldtimer way of laying out an old sheet on the ground in front of your barrel as you shoot(warning...Fire Hazard...Have some water ready). If you see little black tiny bug like things on the sheet that`s your wasted powder. If I were to bet what the max load on a 3 in. 45 cal. would be before little to no more velocity is gained 15 gr. 4f Swiss...c

 

[tenngun]

How much powder is a question back to the bugging of ml
One grain for caliber was an attempt. 45 grains in a .45 is a whumper in a pistol and be too light in a rifle… maybe.
However 35 in a .36 is big but not a killer in a pistol and big but not supper in a rifle.
1/4 ball weight works good in average pistols as a starter. 25 in a .36, 30-35 in a .45, 45 in a .50, but that rule is none to good as size increases (80 in a .62???)
Start small work your way up

 

[winchester1873]

I’m looking to buy a Philadelphia Derringer in .45, it has a 3” barrel. I’ve never shot a BP pistol with such a short barrel before. Can I load it with 45 grains of powder?

Absolutely not. 15 gr. is all you need.

 

[Whughett]

All this brings up the manner in which black powder releases its energy. It’s an explosive which means it releases or burns up all its stored energy in one burst.
Smokeless powders burn at a controlled rate determined by the formulation and the coatings applied during manufacture. It depends on a pressure chamber to work. Black powder doesn’t.

An overly simplistic view probably more complex than that.

 

[Poguetx]

That's a rule of thumb for a rifle starting load, not pistol. I don't think even a Ruger Old Army or Walker could hold 44gr!

 

[Grenadier1758]

I’ve heard that pistols/revolvers should be loaded with grains equivalent to roundball caliber for optimal performance, like 30 grains for a .30 cal, 45 grains for a .45 cal, etc. Is this true? I’m looking to buy a Philadelphia Derringer in .45, it has a 3” barrel. I’ve never shot a BP pistol with such a short barrel before. Can I load it with 45 grains of powder?

I don't know where you heard that. Certainly not on this Forum except for discussions of load development for rifles and even then, that suggestion will depend on the rifle caliber. Most revolvers have a charge capacity that is dependent on the chamber size. Also, the material used for the frame will influence the load. Brass framed revolvers should use a lower charge than a steel framed revolver.

Optimal performance is determined by load development, not some speculation based on caliber.

 

[Wildrangeringreen]

even with 4F, 45gr would be a waste of powder. Probably (just guestimating here) you're looking at 10-15gr of 4F with a ball to be at peak efficiency for that small of a barrel in .45. Little guns like that weren't loaded up all that heavy, mostly because, as others have noted, you don't get any good out of the extra powder. Like Grenadier said, "load development" is how you figure that stuff out.

 

[bang]

It's a rule of thumb for a starting point.

 

[Whughett]

I’ve read the powder charge can be determined by holding the bullet/ball in a cupped palm of one’s hand and pouring powder over until the ball is just covered.
Truth or fiction.
In shot shells, and perhaps muzzle loaders a square load is equal powder and shot by volume.

 

[Wildrangeringreen]

I’ve read the powder charge can be determined by holding the bullet/ball in a cupped palm of one’s hand and pouring powder over until the ball is just covered.
Truth or fiction.
In shot shells, and perhaps muzzle loaders a square load is equal powder and shot by volume.

That depends on how big your hand is, how much you cup your hand, and a bunch of other stuff. Fiction. for .50, I can get down to around 30gr in my hand with that method, if I really scrunch my hand up, or over 80 if I have it more open. A more accurate (and reliable) method would be to take a fraction (1/4 in a pistol, 1/3 in a rifle is a good figure) of the ball's weight, and make that the charge weight.

 

[Whughett]

That depends on how big your hand is, how much you cup your hand, and a bunch of other stuff. Fiction. for .50, I can get down to around 30gr in my hand with that method, if I really scrunch my hand up, or over 80 if I have it more open.

LOL. Maybe most of us are just average size….
I only shoot revolvers so it’s what ever the chamber will hold and still seat a ball below flush with mouth.

I do use the square charge for BP shot shells in an old Remington S/S shotgun.

 

[Smokey Plainsman]

No, it’s nonsense.

 

[Notchy Bob]

I’ve read the powder charge can be determined by holding the bullet/ball in a cupped palm of one’s hand and pouring powder over until the ball is just covered.

Respectfully, I believe this is another rule of thumb relating to rifles. This technique (which I have tried... for rifles) would give you too much powder for a pistol. There was an entire thread devoted to a discussion of this practice on the forum a few months ago. I think @Artificer might have initiated it. Maybe he can weigh in here.

I think this topic is a good one to discuss, though. I've run across several traditional methods for determining a starting powder charge for long guns, but I don't recall seeing any for pistols. It is relatively easy with revolvers, in that you want enough powder for the ball to be seated on it without any air space, but you don't want so much that the ball can't be seated below the cylinder face. Military arms (pistols and revolvers) used charges specified by the Ordnance Department, but the loads were typically pre-measured and put up in paper cartridges. But in working up a load for a civilian single-shot pistol, I don't know.

Best regards,

Notchy Bob

 

[Erwan]

I'm not a pistol shooter, but the empirical rule I have learned from my great-grandfather and grandfather and that I have used for more than sixty-five years is wrong and unsuitable for handguns: too much powder...
In rifles, the rule I learned, and I use, is the grain to the caliber in long arms (for round balls and target shooting) BUT this is a starting load and this needs to be adjusted in relation with the type of arms and the barrel length : this is rarely good at the first shot...

 

[SPQR70AD]

You may have noticed BP many pistols and revolvers have longer barrels than their modern counterparts. This was not out of some form of primitive ignorance or just a fad of the old days. Longer barrel length helps increase power and velocity when using BP much more so than smokeless powder. Using more BP than can be burned before the ball leaves the barrel just amounts to more recoil and wasted BP. A A chronograph will tell you the max load or the oldtimer way of laying out an old sheet on the ground in front of your barrel as you shoot(warning...Fire Hazard...Have some water ready). If you see little black tiny bug like things on the sheet that`s your wasted powder. If I were to bet what the max load on a 3 in. 45 cal. would be before little to no more velocity is gained 15 gr. 4f Swiss...c

also a 7" barrel has a longer loading lever for good leverage seating a ball. cause I got a 5 1/2" 1858 and the lever is shorter and real hard to seat the ball. I got a piece of PVC pipe as a cheater put over the lever

 

[cal.45]

I’ve shot a .44 cap and ball revolver with a 3” barrel but the cylinder add another 1-1.5” to the barrel length. The maximum charge is about 35 grains when compressed, using FFFg you can hear the difference between 25 and 35 grains when it hits a steel target. 15 grains seem to be a very small load even for a 3” derringer, does the 1-1.5” extra barrel length of the revolver really make that much of a difference? I wounder where the sweet spot is, too much powder and you decrease the travel of the bullet (equivalent to a shorter barrel) but a too small charge won’t generate enough pressure too gain maximum velocity.

Searching for an answer I found this chart Black Powder Ballistics Looking at the .44 Remington with a 5.5 inch barrel (cylinder not include) the heaviest charge of 46 grains gave highest velocity. A 6.5-7” barrel is a significant difference compared to the 3” of the Philadelphia Derringer though.

Absolutely not. 15 gr. is all you need.

even with 4F, 45gr would be a waste of powder. Probably (just guestimating here) you're looking at 10-15gr of 4F with a ball to be at peak efficiency for that small of a barrel in .45. Little guns like that weren't loaded up all that heavy, mostly because, as others have noted, you don't get any good out of the extra powder. Like Grenadier said, "load development" is how you figure that stuff out.