Theoretical range card calculations.....

[fohjimmy]

This might be a slightly strange one... I used to be a target shooter many, many years ago and enjoyed the process of zeroing and building range cards immensely. I havent shot for a long time but have recently been playing a PC game based around the US Civil War. I have become somewhat fascinated by the ballistics aspect and i am trying to go through a process of building range cards for rifles like the springfield 1861 and 1853 Enfield etc.

This has been tricky for a number of reasons.

a) I can see where shots land but i have had to reverse engineer target size from the fixed reference dimensions of a rifle.
b) There is no way to ensure the equivalent of a "rested" shot and results are very prone to shooter error.
c) Group sizes become larger than the target at distances beyond 130 yards.
d) While the rifles are based on real world equivalents there is no way to know if the weapon's ammunition or ballistic characteristics are "real world".
e) I have no velocity for the minie ball (except realworld guesstimates which may not be used in the simulation).

I would really like to find out the trajectories of the projectiles from 0-500yards as the main goal.

I have been trying to muddle my way through collecting data and using group calculators to generate the below and seeing if i can find correlations by using big enough groups. I have been looking at online ballistics calculators without much success too. The closest i have come is by calculating the vertical offset of the mean radius of 100 shot groups (to hopefully average out the terrible shooter accuracy). I'm not sure if this can then allow extrapolation out to longer distances...

	Distance (yards)	Shots fired	Group Height (in)	Group Width (in)	Area (in2)	CTC (in)	Mean radius (in)	Offset (vert) in.	MOA CTC	MOA MR
1853	22	80	9.5	9.5	90	11	3	1.6	47.5	13
1853	38	100	16	14.5	232	18	5	1	45	12
1853	68	100	27.5	30	825	30	10	1.1	43	14
1853	128	100	46	47	2162	60	17	-11	45	13

I was wondering if anyone had any ideas or methods for calculating this based on the limited information available. My maths and ballistics was pretty poor to start and is now very rusty! Apologies if this is inappropriate for this forum (not being real world) but it has tickled me and i wonder if it might tickle anyone else...

 

[Phil Coffins]

You need the ballistic coefficient of the bullet, .160-.180 is a good guess. Then the speed, I’m thinking about about 950 FPS maybe. Then plug it into one of the on line calculators.

 

[Rock Home Isle]

ChairGun App gives a .45 calibre sphere a Ballistic Coefficient of 0.0400, .50 calibre sphere 0.0370, .308 calibre sphere 0.0330, .38 calibre sphere o.0300

.20 calibre sphere 0.0150
.22 calibre sphere 0.0170
.25 calibre sphere 0.0200

 

[fohjimmy]

Thank you both, that's a good start. Variable muzzle velocities (ive seen figures from 800-1300 stated, although im guessing the top end is modern powder) are the issue as this makes a huge difference at the 300+ranges.

I've been trying to locate reports from the ordnance department of testing done at the time to see if there is already bullet drop data out there somewhere. I'm guessing they haven't been digitised though. Does anyone know if i can use only the part of the trajectory i have to extrapolate to longer ranges? That might then solve the muzzle velocity/ BC issue.

 

[hawkeye2]

If your chart is based on your computer game then you need to trash the game. A 9.5" group at 22 yards and an almost 4' group at 100 yards is absurd! A 50 yard group should be 2" to 4". Research the BC of an actual Civil War mini and the muzzle velocity too. I chrono graphed my wife's 63 Springfield, 32" barrel, 315 grain semi wadcutter mini, 40 grains GOEX 2f, 950 fps. A 6" square ceramic tile at 100 yards is well within the capabilities of an Enfield or Springfield shooting offhand at a rate of up to 3 shots per minute.

 

[necchi]

Welcome to the forum, and cudo's to your new found interest.
Random target data without actual statistic provenance provides little value.

Actual ballistic data for an individual gun, the projectile and charge can only be found within the hard data of velocity proven.
Meaning, you have to shoot the gun and it's load over a chronograph.
There are other variables to consider within ML shooting, primarily the shooter and his individual loading techniques.

There are guidelines available for a base line (albeit somewhat unreliable). I will provide the links for you here as follows.
https://cva.com/wp-content/uploads/2017/08/Side-lock.pdfhttps://www.tcarms.com/pdfs/uploads/manuals/Hawken_Manual.pdfhttps://ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html
good luck new guy,

 

[fohjimmy]

If your chart is based on your computer game then you need to trash the game. A 9.5" group at 22 yards and an almost 4' group at 100 yards is absurd! A 50 yard group should be 2" to 4". Research the BC of an actual Civil War mini and the muzzle velocity too. I chrono graphed my wife's 63 Springfield, 32" barrel, 315 grain semi wadcutter mini, 40 grains GOEX 2f, 950 fps. A 6" square ceramic tile at 100 yards is well within the capabilities of an Enfield or Springfield shooting offhand at a rate of up to 3 shots per minute.

Hi Hawkeye, to be fair to the game it is trying to recreate the experience of an US Civil War line battle. If those sort of accuracy figures were used then the battles would be fought at 600 yards and a single volley would decide the matter. I can understand why that compromise has been made for gameplay purposes. In a purely target shooting game that would be preposterous of course.

It may have pretty accurate rifle ballistics but they are hidden beneath "sway". The player when aiming is induced to sway so the aim point will move randomly up and down, left and right and there is only a very narrow window to line up the shot and fire.



That is why i fired so many shots and concentrated on the mean radius to try to get an idea of the rifle's characteristics while minimising the introduced inaccuracies of the shooter. Any suggestion, gratefully receieved!

 

[fohjimmy]

Welcome to the forum, and cudo's to your new found interest.
Random target data without actual statistic provenance provides little value.

Actual ballistic data for an individual gun, the projectile and charge can only be found within the hard data of velocity proven.
Meaning, you have to shoot the gun and it's load over a chronograph.
There are other variables to consider within ML shooting, primarily the shooter and his individual loading techniques.

There are guidelines available for a base line (albeit somewhat unreliable). I will provide the links for you here as follows.
https://cva.com/wp-content/uploads/2017/08/Side-lock.pdfhttps://www.tcarms.com/pdfs/uploads/manuals/Hawken_Manual.pdfhttps://ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html
good luck new guy,

Thanks for the welcome and the advice! It is a shame i need those muzzle velocities. Ill try using your links to get some rough ideas but the difference between aiming 100" high and 170" high at longer ranges is pretty extreme so im not sure guesstimates will cut it! Thanks though, more food for thought.

 

[necchi]

Any suggestion, gratefully receieved!

You lost the opportunity twice with the game's presentation, once at 8 and another at a late 14.

 

[fohjimmy]

You lost the opportunity twice with the game's presentation, once at 8 and another at a late 14.

The rifle was unloaded, i was just demonstrating the amount of sway. That was the 22 yard target.

 

[ResearchPress]

. . . . .
e) I have no velocity for the minie ball (except realworld guesstimates which may not be used in the simulation).

I would really like to find out the trajectories of the projectiles from 0-500yards as the main goal.
. . . . .

Testing by the Ordnance Select Committee in 1862. With a Pattern 1853 Enfield (3 groove, 1 in 78 pitch, progressive depth rifling) and 530 grain bullet .55 dia / wood plug, 2.5 drams charge, initial velocity was recorded as 1265 fps. At 90 feet, 1206 fps.

Navez Electro-Ballistics Apparatus saw use in Great Britain for measuring velocity with both small arms and artillery.

Here in the UK I shoot Enfield rifle out to 600 yards, occasionally 800 yards. The target frame size at 600 yards is 70 inch wide x 60 inch high. I’d don’t expect to miss the target at that range, but sometimes do. In windy conditions I can be aiming off (remember there’s no windage adjustment on Enfield rifles) another half target width. Changes in wind strength can make a significant difference to point of impact. Shooting is prone with the military sling the only support.

David

 

[fohjimmy]

Thank you, much appreciated David. The charge indicated in the select committee test is a little lower (68 vs 70 grain) than that listed in "Ammunition for Small Arms now used in the C. S. Service". The US "Ordnance Manual of 1861" gives a standard .577 cartridge containing 60gr though (albeit a 500grain bullet). I had expected the muzzle velocity to be a little lower than that, so very interesting.

If it is not too much trouble would you have an idea of whether the bullet drop conforms with modern ballistics calculators?

 

[ResearchPress]

Thank you, much appreciated David. The charge indicated in the select committee test is a little lower (68 vs 70 grain) than that listed in "Ammunition for Small Arms now used in the C. S. Service". The US "Ordnance Manual of 1861" gives a standard .577 cartridge containing 60gr though (albeit a 500grain bullet). I had expected the muzzle velocity to be a little lower than that, so very interesting.

If it is not too much trouble would you have an idea of whether the bullet drop conforms with modern ballistics calculators?

My information relates to British sources, hence the 2.5 dram charge which was the service rifle charge.

As you note, I have the Springfield Rifle Musket during the Civil War as 500 grain bullet fired with 60 grains of musket powder (C. Fuller, ‘The Rifled Musket’, 1958). Others may have information relating to this rifle and muzzle velocity. With the lighter bullet, reduced powder charge, different powder and different form of cartridge the Springfield and Enfield won’t have direct correlation on trajectory.

I’ve never used modern ballistic calculators - just practical experience working back through the ranges to gain elevation settings.

David

 

[fohjimmy]

Aaah ok. Thank you.