calculating black powder loads? - The Firearms Forum

lansdale · 04-08-2011, 03:11 PM

hi everybody,

i was just wondering, is it possible to calculate black powder loads for a certain rifle?

i own a 1874 swedish rolling block.
it has a .58 caliber straight rifled barrel, with a 28 gauge chamber.

on Tom Bullocks site if found that a 28 gauge black powder shotgun cartridge usually has 55 grains of 2FG powder, and 3/4 Oz of lead shot (which is 328 grains).

so if this ratio of 55 grains powder for 328 grains of shot is right, could i use this ratio to calculate the amount of powder needed for a heavier shot load?

lets say (in theory) i'd want to use a shot load of 1 Oz (437 grains).

(55 grains / 328 grains) * 437 grains = 73 grains of powder

i know about the "equal volume loads" principle they use with black powder shotguns.

so i tried to check the calculation i made above, by calculating the volume of blackpowder and the volume of the shot.

235 grains of 2FG blackpowder = 1 cubic inch,
so 73 grains of 2FG blackpowder is (1 / 235) * 73 = 0.3106 cubic inch

lead has a density of 2868 grains per cubic inch
so 0.3106 cubic inch * 2868 grains = 890.8 grains of lead.
because 1 cubic inch of lead shot consists of 1/2 lead and 1/2 of empty space, the weight of 0,3106 cubic inch of lead shot would only be half of the 890.8 grains.

this would mean 445 grains of lead shot with 73 grains of powder when calculated with the "equal volume loads" principle.

with the "ratio" calculation i calculated 437 grains of lead shot with 73 grains of powder. a difference of 8 grains which is about 1.8%

some of you (maybe all of you) probably ask "why would you want to calculate something like that?"

well the thing is where i live it's nearly impossible to find 28 gauge blackpowder cartridges, and we are only allowed to buy and use them if we join a skeet club. to use the rolling block at my usual shooting club i would need to load brass shotgun shells with .58 cast bullets, which ofcourse are almost always a lot heavier than 328 grains. to do that i would need load data...which i cant find anywhere.

so my question at the end is, could someone give me advice about these calculations? i'd use them as a maximum load and load my cartridges a little lighter to be on the safe side.

TUCO-the-ratt · 04-08-2011, 04:05 PM

ALL Black powder cartridges must be loaded so as to have absolutely no air gap under the bullet/shot and generally should have at least some compression on the powder charge.

I know this sounds suicidal to anyone used to loading smokeless but the rules are all different for black powder.

Here's a link to black powder cartridge loading

http://www.wahsatchdesperadoes.com/I...CR_Loading.pdf

Hawg · 04-08-2011, 04:09 PM

You don't need all the calculations. Use an equal amount of shot to powder in shotshells. Less powder than shot for a tighter pattern and more powder than shot for a wider pattern. For cartridges fill the case to 1/16 of top and seat bullet of your choice. if you want a lighter load use cornmeal for a filler. Never load bp with an air gap, it must be compressed.

lansdale · 04-08-2011, 04:34 PM

so does that mean the amount of bp doesnt make the rifle blow up?

i knew air space between the powder and bullet is lethal, but i thought the amount of powder was important too when in comes to not blowing up the rifle?

myfriendis410 · 04-08-2011, 04:50 PM

Black powder doesn't burn; it explodes. It does so at a fixed velocity and a peak pressure which is way lower than progressive burning smokeless powder. Excess black powder will just spew out the muzzle. The oldtimers with their muzzleloaders would start with a patched round ball and around 50 gr. of powder and shoot in the snow while increasing the charge by five grain increments until powder started speckling the snow in front of them. That would be a max charge.

ofitg · 04-08-2011, 05:59 PM

lansdale, your description left me wondering - according to what I have read, the Swedish rolling block was originally chambered for the 12.17x44R rimfire cartridge.... but the book Cartridges for Collectors vol.4 states that they were later converted to centerfire. This book also lists the bullet diameter as .528 inches. Are you certain that your bore is .58 caliber?

lansdale · 04-09-2011, 06:50 AM

Quote:

Originally Posted by ofitg

lansdale, your description left me wondering - according to what I have read, the Swedish rolling block was originally chambered for the 12.17x44R rimfire cartridge.... but the book Cartridges for Collectors vol.4 states that they were later converted to centerfire. This book also lists the bullet diameter as .528 inches. Are you certain that your bore is .58 caliber?

when i bought the rifle i wanted to make sure about the exact bore diameter so i made a casting of the camber and the first 2 inches of the barrel, and i did slug the bore with an oversized lead ball.

the diameter measured between the grooves varies between 0.5799 and 0.5838

the diameter measured between the lands varies between 0.5530 and 0.5570

the barrel is marked 1870 while the action is marked 1874.
i didnt really understand it either. i read about .58 caliber rolling blocks, and 12.7 rolling blocks, but i couldnt find info about one with .58 barrel with a 28 gauge chamber

oh and ofcourse thanks to everyone for replying, i really didnt know about the amount of blackpowder that could be used. i do remember the "dont leave any space between bullet/shot and the powder" my granddad always said

ofitg · 04-09-2011, 11:15 AM

lansdale, I found the following load data for 12.17x44R in the book, Cartridges of the World -

Bullet 345 grains ..... Powder 76 grains Fg .... Muzzle Vel 1300 ft/sec

If I were doing it, I would probably start off with 50 grains of powder out of respect for the gun's age, and fill up any empty case volume with an inert filler like cornmeal.

If I may ask, what are the chamber dimensions, based upon your chamber cast?

lansdale · 04-09-2011, 12:55 PM

base diameter is about .626
diameter at the end of the chamber, at 65mm, is about .614

the rifling starts almost immediately, like in a normal rifle. not a long cone like shotguns usually have.

the barrel has 8 grooves and 8 lands

ofitg · 04-09-2011, 04:10 PM

I can see why you refer to it as a 28 gauge chamber - your measurements are practically an exact match for the dimensions at http://www.dave-cushman.net/shot/shotshellloads.html

The book Cartridges for Collectors vol.1 lists a couple of .58 rounds which were ostensibly based upon 28 ga brass hulls - I am attaching the illustrations below.

Unfortunately, both of these cartridges appear to be too fat to fit into your chamber.

I don't have any 28 ga brass or .58 bullets to play with - I am wondering if you might have some difficulty getting the .58 projectile to seat down into the 28 ga hull?

lansdale · 04-09-2011, 06:14 PM

thanks for the info, it tried looking up all sort of old ammo on the internet but didnt see these two.

according to circlefly.com 28 gauge magtech brass shells have an inside diameter of approx .585

i'll have to order a box of them as soon as i get 28 gauge shells and .58 bullets registered on my license (thats how it has to be done in my country, it's a pita) to check if and how .58 bullets fit.

depending on how loose they are i could probably paper patch them if they're a bit loose. i think that would be better than using a crimp each time.

ofitg · 04-09-2011, 07:49 PM

It seems odd that the 15x40R and 15x49R cartridges are slightly too fat to fit into a standard 28 ga chamber.... perhaps the 28 ga chambers were more "generous" back in the 1800s, and your rifle was converted sometime later when the shotshell specifications had been tightened up a bit (?)

It sounds like you have an interesting project there. If you have access to the Lyman Blackpowder Handbook, it can provide a wealth of ballistic/loading data.

Getting back to your original question, I might offer the following observations -

With everything else (bullet weight, bore size, etc) held constant, increasing the powder charge will increase pressures.
With everything else (powder charge, bore size, etc) held constant, increasing the bullet weight will increase pressures.

Here are four loads from the ".58 caliber" section of the Lyman Blackpowder Handbook -

Round Ball (260 gr) .... Powder 50 gr FFg .... Pressure 2960 LUP .... Velocity 863 ft/sec

Round Ball (260 gr) .... Powder 90 gr FFg .... Pressure 5370 LUP .... Velocity 1162 ft/sec

570 gr Minie #57730 .... Powder 50 gr FFg .... Pressure 3780 LUP .... Velocity 729 ft/sec

570 gr Minie #57730 .... Powder 90 gr FFg .... Pressure 9710 LUP .... Velocity 1001 ft/sec

I would note that ".58" military cartridges such as the U.S. .58 Musket (Berdan) and the British .577 Snider used bullets weighing about 480 gr with powder charges in the neighborhood of 70-80 gr. Those rifles generated quite a bit of recoil, perhaps more than you would enjoy for recreational purposes.

Please keep us posted on your project!

ElvinWarrior · 04-15-2011, 09:22 PM

Mountain man method...

Put the ball or lay the conical down in the palm of your hand...

Carefully pour BP onto the ball, or conical, until a nice little cone of powder completely covers the lead, but just barely...

This is a good, off the cuff, way of measuring the powder, it is self regulating, in that the size of the lead, adjusts the amount of powder.

I tested this many times when I was younger, carefully pouring out the powder, and carefully transferring it into a gradiated powder measure to see where the grainage came out... Damn near right on EVERY TIME !!!!

Always remember the "KISS" method guys, "Keep It Simple Stupid". Back in the old days, or even today if you decide to go up Alaska way and homestead 20 Acres, being a mountain man, (Ya, you can STILL HOMESTEAD in a few very remote places !!!) They didn't carry around with them a 20lb bag of possibles, or fancy brass measures or any kind of St. Louis Sissy banjangles like that at all... they lived in the dirt and grit by their wits and know how... THINK !!!)

Sincerely,

ElvinWarrior... aka... David, "EW"

Hawg · 04-24-2011, 11:51 AM

Actually mountain men did use measures. Usually a piece of antler hollowed out to hold the correct ammount but some used fancy bought measures. Some powder horns of the day had built in measures. Some used a hollow horn plug as a measure. Most tailored their loads for the game they were after and used several different powder charges so a couple or three measures were a must have.

04-08-2011, 03:11 PM	#1
lansdale Member Join Date: Apr 2011 Posts: 5	calculating black powder loads? hi everybody, i was just wondering, is it possible to calculate black powder loads for a certain rifle? i own a 1874 swedish rolling block. it has a .58 caliber straight rifled barrel, with a 28 gauge chamber. on Tom Bullocks site if found that a 28 gauge black powder shotgun cartridge usually has 55 grains of 2FG powder, and 3/4 Oz of lead shot (which is 328 grains). so if this ratio of 55 grains powder for 328 grains of shot is right, could i use this ratio to calculate the amount of powder needed for a heavier shot load? lets say (in theory) i'd want to use a shot load of 1 Oz (437 grains). (55 grains / 328 grains) * 437 grains = 73 grains of powder i know about the "equal volume loads" principle they use with black powder shotguns. so i tried to check the calculation i made above, by calculating the volume of blackpowder and the volume of the shot. 235 grains of 2FG blackpowder = 1 cubic inch, so 73 grains of 2FG blackpowder is (1 / 235) * 73 = 0.3106 cubic inch lead has a density of 2868 grains per cubic inch so 0.3106 cubic inch * 2868 grains = 890.8 grains of lead. because 1 cubic inch of lead shot consists of 1/2 lead and 1/2 of empty space, the weight of 0,3106 cubic inch of lead shot would only be half of the 890.8 grains. this would mean 445 grains of lead shot with 73 grains of powder when calculated with the "equal volume loads" principle. with the "ratio" calculation i calculated 437 grains of lead shot with 73 grains of powder. a difference of 8 grains which is about 1.8% some of you (maybe all of you) probably ask "why would you want to calculate something like that?" well the thing is where i live it's nearly impossible to find 28 gauge blackpowder cartridges, and we are only allowed to buy and use them if we join a skeet club. to use the rolling block at my usual shooting club i would need to load brass shotgun shells with .58 cast bullets, which ofcourse are almost always a lot heavier than 328 grains. to do that i would need load data...which i cant find anywhere. so my question at the end is, could someone give me advice about these calculations? i'd use them as a maximum load and load my cartridges a little lighter to be on the safe side. -->

04-08-2011, 04:05 PM	#2
TUCO-the-ratt Member Join Date: Mar 2011 Posts: 26	Re: calculating black powder loads? ALL Black powder cartridges must be loaded so as to have absolutely no air gap under the bullet/shot and generally should have at least some compression on the powder charge. I know this sounds suicidal to anyone used to loading smokeless but the rules are all different for black powder. Here's a link to black powder cartridge loading http://www.wahsatchdesperadoes.com/I...CR_Loading.pdf

04-08-2011, 04:09 PM	#3
Hawg Advanced Senior Member Join Date: Mar 2011 Posts: 1,554	Re: calculating black powder loads? You don't need all the calculations. Use an equal amount of shot to powder in shotshells. Less powder than shot for a tighter pattern and more powder than shot for a wider pattern. For cartridges fill the case to 1/16 of top and seat bullet of your choice. if you want a lighter load use cornmeal for a filler. Never load bp with an air gap, it must be compressed.

04-08-2011, 04:34 PM	#4
lansdale Member Join Date: Apr 2011 Posts: 5	Re: calculating black powder loads? so does that mean the amount of bp doesnt make the rifle blow up? i knew air space between the powder and bullet is lethal, but i thought the amount of powder was important too when in comes to not blowing up the rifle?

04-08-2011, 05:59 PM	#6
ofitg Advanced Senior Member Join Date: Feb 2010 Contributor Posts: 1,447	Re: calculating black powder loads? lansdale, your description left me wondering - according to what I have read, the Swedish rolling block was originally chambered for the 12.17x44R rimfire cartridge.... but the book Cartridges for Collectors vol.4 states that they were later converted to centerfire. This book also lists the bullet diameter as .528 inches. Are you certain that your bore is .58 caliber? Last edited by ofitg; 04-08-2011 at 06:53 PM..

04-08-2011, 04:50 PM	#5
myfriendis410 Senior Member Join Date: Mar 2011 Location: Lompoc California Posts: 542	Re: calculating black powder loads? Black powder doesn't burn; it explodes. It does so at a fixed velocity and a peak pressure which is way lower than progressive burning smokeless powder. Excess black powder will just spew out the muzzle. The oldtimers with their muzzleloaders would start with a patched round ball and around 50 gr. of powder and shoot in the snow while increasing the charge by five grain increments until powder started speckling the snow in front of them. That would be a max charge. __________________ Life's too short to shoot an ugly gun.....

04-09-2011, 11:15 AM	#8
ofitg Advanced Senior Member Join Date: Feb 2010 Contributor Posts: 1,447	Re: calculating black powder loads? lansdale, I found the following load data for 12.17x44R in the book, Cartridges of the World - Bullet 345 grains ..... Powder 76 grains Fg .... Muzzle Vel 1300 ft/sec If I were doing it, I would probably start off with 50 grains of powder out of respect for the gun's age, and fill up any empty case volume with an inert filler like cornmeal. If I may ask, what are the chamber dimensions, based upon your chamber cast? Last edited by ofitg; 04-09-2011 at 11:25 AM..

04-09-2011, 12:55 PM	#9
lansdale Member Join Date: Apr 2011 Posts: 5	Re: calculating black powder loads? base diameter is about .626 diameter at the end of the chamber, at 65mm, is about .614 the rifling starts almost immediately, like in a normal rifle. not a long cone like shotguns usually have. the barrel has 8 grooves and 8 lands

04-09-2011, 04:10 PM	#10
ofitg Advanced Senior Member Join Date: Feb 2010 Contributor Posts: 1,447	Re: calculating black powder loads? I can see why you refer to it as a 28 gauge chamber - your measurements are practically an exact match for the dimensions at http://www.dave-cushman.net/shot/shotshellloads.html The book Cartridges for Collectors vol.1 lists a couple of .58 rounds which were ostensibly based upon 28 ga brass hulls - I am attaching the illustrations below. Unfortunately, both of these cartridges appear to be too fat to fit into your chamber. I don't have any 28 ga brass or .58 bullets to play with - I am wondering if you might have some difficulty getting the .58 projectile to seat down into the 28 ga hull? Attached Images

04-09-2011, 06:14 PM	#11
lansdale Member Join Date: Apr 2011 Posts: 5	Re: calculating black powder loads? thanks for the info, it tried looking up all sort of old ammo on the internet but didnt see these two. according to circlefly.com 28 gauge magtech brass shells have an inside diameter of approx .585 i'll have to order a box of them as soon as i get 28 gauge shells and .58 bullets registered on my license (thats how it has to be done in my country, it's a pita) to check if and how .58 bullets fit. depending on how loose they are i could probably paper patch them if they're a bit loose. i think that would be better than using a crimp each time.

04-09-2011, 07:49 PM	#12
ofitg Advanced Senior Member Join Date: Feb 2010 Contributor Posts: 1,447	Re: calculating black powder loads? It seems odd that the 15x40R and 15x49R cartridges are slightly too fat to fit into a standard 28 ga chamber.... perhaps the 28 ga chambers were more "generous" back in the 1800s, and your rifle was converted sometime later when the shotshell specifications had been tightened up a bit (?) It sounds like you have an interesting project there. If you have access to the Lyman Blackpowder Handbook, it can provide a wealth of ballistic/loading data. Getting back to your original question, I might offer the following observations - With everything else (bullet weight, bore size, etc) held constant, increasing the powder charge will increase pressures. With everything else (powder charge, bore size, etc) held constant, increasing the bullet weight will increase pressures. Here are four loads from the ".58 caliber" section of the Lyman Blackpowder Handbook - Round Ball (260 gr) .... Powder 50 gr FFg .... Pressure 2960 LUP .... Velocity 863 ft/sec Round Ball (260 gr) .... Powder 90 gr FFg .... Pressure 5370 LUP .... Velocity 1162 ft/sec 570 gr Minie #57730 .... Powder 50 gr FFg .... Pressure 3780 LUP .... Velocity 729 ft/sec 570 gr Minie #57730 .... Powder 90 gr FFg .... Pressure 9710 LUP .... Velocity 1001 ft/sec I would note that ".58" military cartridges such as the U.S. .58 Musket (Berdan) and the British .577 Snider used bullets weighing about 480 gr with powder charges in the neighborhood of 70-80 gr. Those rifles generated quite a bit of recoil, perhaps more than you would enjoy for recreational purposes. Please keep us posted on your project!

04-15-2011, 09:22 PM	#13
ElvinWarrior Member Join Date: Mar 2011 Location: Los Angeles California, USA Posts: 34	Re: calculating black powder loads? Mountain man method... Put the ball or lay the conical down in the palm of your hand... Carefully pour BP onto the ball, or conical, until a nice little cone of powder completely covers the lead, but just barely... This is a good, off the cuff, way of measuring the powder, it is self regulating, in that the size of the lead, adjusts the amount of powder. I tested this many times when I was younger, carefully pouring out the powder, and carefully transferring it into a gradiated powder measure to see where the grainage came out... Damn near right on EVERY TIME !!!! Always remember the "KISS" method guys, "Keep It Simple Stupid". Back in the old days, or even today if you decide to go up Alaska way and homestead 20 Acres, being a mountain man, (Ya, you can STILL HOMESTEAD in a few very remote places !!!) They didn't carry around with them a 20lb bag of possibles, or fancy brass measures or any kind of St. Louis Sissy banjangles like that at all... they lived in the dirt and grit by their wits and know how... THINK !!!) Sincerely, ElvinWarrior... aka... David, "EW" __________________ God Made Man, But COLT Made Them Equal !!! Last edited by ElvinWarrior; 04-15-2011 at 09:31 PM..

04-24-2011, 11:51 AM	#14
Hawg Advanced Senior Member Join Date: Mar 2011 Posts: 1,554	Re: calculating black powder loads? Actually mountain men did use measures. Usually a piece of antler hollowed out to hold the correct ammount but some used fancy bought measures. Some powder horns of the day had built in measures. Some used a hollow horn plug as a measure. Most tailored their loads for the game they were after and used several different powder charges so a couple or three measures were a must have.