Powder Loads and Velocities

[Zonie]

From time to time someone asks about powder loads and velocities for their guns.
This usually turns into a great debate about what is a MAXIMUM load and what is a MAXIMUM EFFICIENT load.

What I'm about to present here won't really answer the question about Maximum Efficient loads but I am going to say right up front that our muzzleloaders usually have a MAX LOAD recommended by their manufacturer. DO NOT EXCEED THAT MAXIMUM. DOING SO CAN RESULT IN YOUR DEATH OR WORSE Like being permanently disfigured or blinded for life. .

Now, with that out of the way lets get into what I did.
I went to my 2nd Ed of the "LYMAN BLACK POWDER HANDBOOK & LOADING MANUAL" and used their data to create graphs for the .45, .50, .54 and .58 caliber rifles.
These were all Percussion guns.
The velocities are muzzle velocities.
Depending on the caliber I charted several different powders including Goex, Elephant and Pyrodex. The powders are shown at the right side of the charts.
The barrels specifications are also shown at the right side of the chart.

I have heard about some formulas which give a maximum efficiency value which is determined by the volume of the barrel.
In some of these charts I see indications that there is a breaking off point where the chart changes direction indicating that the efficiency has decreased above some load size but this seems to be related to the type of powder used as well the bore volume. Some powders don't seem to be "volume" sensitive.

Please keep the discussions on a gentlemanly level.

The first chart is for the .45 caliber rifle with a Percussion barrel 28 inches long shooting a .440 diameter roundball. Twist is 1:48 and the powder charges range from 40 to 120 grains.

The second chart is for the .50 caliber rifle with a Percussion barrel 32 inches long shooting a .490 diameter roundball. Twist is 1:60 and the powder charges range from 40 to 120 grains.

The third chart is for the .54 caliber rifle with a Percussion barrel 28 inches long shooting a .535 diameter roundball. Twist is 1:48 and the powder charges range from 40 to 120 grains.

The fourth chart is for the .58 caliber rifle with a Musket capped 32 inch barrel shooting a .570 diameter roundball. Twist is 1:48 and the powder charges range from 60 to 140 grains.

 

[Bountyhunter]

Good stuff, Zonie, Thanks.

I presume that with 60" and 66" twists, we will get a smidgeon better velocity due to lack of friction, as opposed to the 48" twists.

 

[Zonie]

First off, I don't know.
What I do know is things like the effect of twist can do things that may not make sense.
I've read somewhere that the faster twists can actually increase velocity.
As I recall, the ball initially resists acceleration due to the faster twist and this allows the powder to burn more completely which creates more pressure. The increased pressure finally wins the contest and ends up pushing the ball out of the barrel faster than if the gun had a slow twist.
This effect is sometimes seen in smooth rifles or smoothbores shooting patched roundballs.

Of course, I don't have the proof in front of me and I might be wrong. :grin:

 

[BrownBear]

Nice way to see the results Jim. Most of us see and understand "shape" better than numbers. Thanks for your efforts!

I agree that they probably won't change any minds, but I can foresee your charts becoming a permanent feature of the reference section of the site.

Nothing there to change my mind, but my wife's been trying to do that without success for 40 years. :yakyak:

 

[CoyoteJoe]

Interesting chart Zonie, but it seems to be missing the horizontal numbers.

 

Zonie,

Thanks pard. That coincides perfectly with info Paul V. gave me on a PT we had a bit back. 90 grns. of RS was killing my shoulder in my T.C. Hawken .50 He told me then that for the velocity return 90 grns. was a waste and a punisher. If I'm reading your chart properly it is.

Thanks again,
Jay

 

[douglas duncan]

it says that you are using a .490 round ball with the 54 cal. is this a typo?

 

[roundball]

That's a lot of work Zonie, thanks..facts from chronographs cut through the fog and noise level.
:hatsoff:

The calibers I've tested to date have shown the same kinds of slopes, although I haven't done the .54cal yet, and noted the 2F trend line on the .54cal had a minor sag in it...be interesting to see what my .54cal plots when I run it...thanks again

 

[Semisane]

Excellent display Zonie.

For hunting loads I hold to the philosophy that "velocity is energy and energy is good". For my .54 Great Plains flintlock I push it until accuracy starts to fall off. In my gun that's 95 grains GOEX FFFg.

 

[renovato]

Great charts, Zonie. That should help folks visualize what's going on at different load levels. It'll be a handy reference when the topic comes up again.

I'm with BrownBear. As I was looking at the charts, I thought they should be stickied.

 

[paulvallandigham]

If you click on the T/c Website, they have loading data for their guns.
http://www.tcarms.com/assets/manuals/current/Shooting_TC_Side_Lock_Black_Powder_
Guns.pdf

I took this from their info on their .50 caliber rifles shooting a .490 PRB.

50 grains FFG----1357 fps.
60 grains FFg----1434 fps.**** Gain of: 77 fps.
70 grains FFg----1643 fps.**** " " 209 fps.!!
80 grains FFg----1838 fps.**** " " 195 fps.

Note: A 33 inch .50 caliber barrel should have a maximum Efficient burning load
of 74.51 grains.

90 grains FFg----1950 fps **** " " 112 fps.
100 grains FFg---2052 fps.**** " " 102 fps.
110 grains FFg---2135 fps.**** " " 83 fps.


The numbers on your Right are the increase or loss of velocity for each 10 grain increment of BLACK Powder using the T/C data. YOu get those numbers by subtracing the next lower velocity from the velocity for the charge you are interested in.

Most of the T/C guns have or had 32 or 33 inch barrels. Barrels longer than that tend to be after-market " drop-in" barrels.

Please understand:

1. This is not data I produced out of my gun.

2. This is data from the Manufacturer of the most common Factory produced ML rifle in this country. Its their numbers, not mine.

3. The Davenport formula works as represented.

4. I don't know if the Davenport formula works with the substitute powders. Charles Davenport died years before any of these powders, including Pyrodex, were invented. The U.S. Navy was not using substitute powders for their " GUNS ". He was only interested in helping MLers find the most accurate, and efficient powder charge for their particular gun, using BLACK POWDER.

5. The only reason I put the information on this forum about the Davenport formula was to help other MLer shooters find their most accurate load, too.

P.S. Oh, I have never gotten these kinds of velocities using my 39" barreled .50 caliber rifle shooting PRB with .490 ball and .015" patching.

This data may have been generated by factory test barrels, in controlled conditions you are not likely to achieve elsewhere. Like many data for modern ammo, shooting the same ammo in your gun may not produce those higher velocities.

:thumbsup:


Please accept my apology for the crooked alignment of the numbers on the right side. They line up when I typed them here, but in posting, the site pulls them together.

 

[Bountyhunter]

:thumbsup:

Well, if that isnt the way it works, then we will always think that it should have been that way. :grin:

 

[Zonie]

The .490 ball in the .54 chart is a typo. The text above it is correct when it says .535 diameter ball.

The reason the horizontal values aren't posted is because I don't know how to get my Quattro Pro to put them in and I figured if I fudged them with text they would come out looking like I fudged them. Look at the text above the chart to see what the powder load range is. The low value is the first square at the left side of the chart and the high value is the last square on the right side of the chart.

I'm surprised at you folks.
I figured that by now someone would have said, "I shoot the little caliber guns. Why didn't you include the .32 and .36?"

Well, just to head you off at the pass, here they are:

.32 Caliber, 26 inch barrel percussion shooting a .310 diameter ball. Powder loads are from 30 thru 70 grains.

.36 Caliber, 28 inch barrel percussion shooting a .350 diameter ball. Powder loads are from 30 thru 70 grains.

I notice that as the calibers sizes come down on all of these charts the "break" point for load efficiency becomes much more pronounced.

 

[tjohnson56]

Zonie, it looks to me like the most consistent caliber is the .58, there seems to be very little sag in the lines no matter what powder is used. Would this be because of the musket caps, barrel length or is it still under the Davenport formula?

 

[reddog]

If it ain't,,,it sure missed a good opportunity!!Surprised ya had to ask. Hang in there.

 

[Zonie]

I'm not sure what the reason is but it does seem to bear out the idea that the smaller the bore the more "fussy" the gun is about its powder load.

Just for giggles, I've charted the 12 guage.
This is for a 12 guage smoothbore shooting a patched .690 diameter ball thru a 26 inch modified choke barrel using a .020 Ox-Yoke patch.
The powder loads and velocities are down from the rifle loads which I imagine is due to the thin walls of the barrel.
As you can see, at least some of the old Elephant powder wasn't all that bad.

I also figured out how to add the horizontal (X) load information.

 

[longcruise]

Nice graphs, Zonie. Thanks for posting.

I see that both the Davenport School and the Linear School seem to think the graphs vinicate their POV. :rotf:

 

[Zonie]

I got to thinking about the questions about twist and thought a look at two different twists would be interesting.

Unfortunatly Lymans book didn't have charts for the same barrel length with different twists so I made this chart which shows several variables.
It is for a .50 caliber roundball using GOEX powders.
Both of the barrels were loaded with a .490 diameter roundball patched with .015 thick Ox-Yoke patches.

The 28 inch barrel has a 1:48 twist.
The 32 inch barrel has a 1:60 twist.

I don't pretend to know whether the twist or the barrel length had the largest effect on the final muzzle velocities but I think it is interesting to compare them.

 

[paulvallandigham]

A 26 inch 12 gauge bore( .72") will use 121.73 grains of powder efficiently, per the Davenport Formula. Zonie's " Chart " does not calculate the velocity for that amount of powder, or above, to show the breaking point.

Not that this would make a bit of difference to you, but others might like to know. :hmm: :hatsoff:

 

[roundball]

More good work Zonie, thanks!
:hatsoff:

Also glad to see 3F repeatedly shows to be a consistent great performer across the board like it showed in my chronograph tests, because Goex 3F has been outstanding for me in all Flintlocks from .40 -.62cal...

:thumbsup: