Updated - Original Spencer Cartridge Ballistics - Updated

[w44wcf]

Updated.....
Here are the test results based on the firearms referenced below.....

.56-46 (45 grs. b.p. / 330 gr)  - 1,183 f.p.s. average
.56-50 (45 grs. b.p. / 350 gr)  - 1,093 f.p.s. average  (ndnchf data - see post below) Thank you! 
.56-56 (45 grs. b.p. / 350 gr)  - 1,053 f.p.s. average

.56-52 (45 grs. b.p. / 400 gr)  - 1,025 f.p.s. average

matt45,
It would be interesting to see how these velocities compare to those in the Malcot book.
If you would post them it would be much appreciated.

Thank you,
w44wcf

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Howdy,
I am doing some research on the ballistics of the original Spencer Cartridges.
The data below is from Cartridges Of The World....

ctg.............   bullet grs....   charge grs..   ballistics fps
56-46.........   320-330.....   45..............   1210 est  
56-50.........   350............   45..............   1230 est (not correct)
56-52.........   400............   45..............   1200 est (not correct)
56-56.........   350-360.....   45..............   1200 est (not correct)

Based on my testing of heavy bullets with b.p. in a .45 Colt Rifle, the 1210 f.p.s. est for the .56-46 cartridge is almost "spot on".
I will retest using the .45 Colt rifle and then using a .54 Muzzleloader to approximate the .56-52 and .56-56 cartridges.

Since the larger calibers have a larger expansion ratio, and use the same powder charge, the velocities would be progressively lower as the bore size increases which means that the est velocities for the .56-50, .56-52, and .56-56 are likely not correct.

I was wondering if there is any other published data that would give the correct ballistics for each cartridge (?).

Thank you,
w44wcf  

[matt45]

The issue to me is how does one determine published velocities are incorrect w/ out testing the cartridges?  Marcot's book lists some of the velocities, and I would, on the absence of other data, take that as a starting point.

[w44wcf]

Matt45,

Thank you for the Marcot book reference. Unfortunately I do not have that book and my principal interest is actually more in the original ballistics of obsolete cartridges.

I have previously done a study of the Henry cartridges, purchasing some original cartridges, dissecting them and using the original powder and same weight bullets for a ballistic study and then to see what current b.p.'s had similar ballistic strengths and thus would produce similar ballistics.  A story for another time....

Anyway, regarding  "how does one determine published velocities are incorrect".....  Cartridges Of The World indicated that they were estimates other than actual.  If the  same powder was used at the same charge weight in all the Spencer cartridges, then ballistically, the velocities would indeed be lower as the bore size increases since there is more volume for the gas to expand in which means less pressure which = less velocity.

Now in the case where specific powders with different ballistic strengths were assigned to each cartridge, the above would not be true.

I am going on the assumption that the same powder type was used (different lots obviously) for all the Spencer cartridges but the question would be what powder?

I have made a choice (wrong or right or partially correct) based on the powder used in the Henry cartridges and will be testing a modern black powder with a similar ballistic strength.   I will be using 45 grs. by weight with a 330 gr. bullet in a .45 caliber (.45 Colt rifle) and 350 gr. bullet in a .54 Cal. muzzleloader.  

I'll post when I have the results.  It would be interesting to compare my test velocities  to those in the Marcot book if you would be so kind as to post them.

Thank you,
w44wcf    

[Herbert]

You also have to take into acount the large amount of priming powder used in the large rimfire cartridges,this will add velocity.Sprinfield and Winchester have published ballistic results for the Spencer cartridges,but I just can not find them at present

[w44wcf]

Herbert,
Good point. I have tested different strength primers in different b.p. ctg's (large rifle, large rifle magnum, large pistol) and did not find any real significant difference between them. Interestingly, in a couple of applications the large pistol primers actually produce slightly higher velocities.

w44wcf

[matt45]

Herbert is spot on vis-aviz priming component, etc.  To put it plainly, it is impossible to replicate the velocities the old timers achieved with modern components

[w44wcf]

matt45,
That may be since there would be more priming compound in the rim of the Spencer ctgs. than the .44 Henry. 

In the case of the .44 Henry, the original powder I removed from some Henry rounds and tested, generated a surprisingly close 1,131 f.p.s. as compared to the Winchester catalog velocity of 1,125 f.p.s.  Primer used in that instance was large pistol.

w44wcf

[w44wcf]

Updated - please see first post.

w44wcf

[Trailrider]

One thing you need to take into account is the Relative Sectional Densities of the different bullets being used in different cartridges. Relative Sectional Density (RSD) is the bullet weight in grains divided by 7000 gr/lb, divided by the square of the bullet diameter.  For example a 250 gr. .45 bullet has an RSD of .175.  An equivalent .515" diameter bullet would weigh 325 gr.

Your 330 gr .45 cal. bullet has an RSD of .231, whereas a 350 gr .54 cal. bullet has an RSD of only.171.  Using the same powder charge for the "lighter" .54 cal. bullet will result in .171/.231 = .74. No, that's not the velocity that will result; it's the resultant energy.  Let's say the 330 gr .45 has a MV of 1250 ft/sec.  The muzzle energy comes out to 1145 ft-lbs.  Multiply that by .74 and you come out with 847 ft-lbs. Calculating the resultant MV, you wind up with 1043 ft/sec.

I don't have a .56-50, but some years ago I ran tests on a .56-56 using cutdown .50-70 brass and 411 gr bullets. The bullet diameters are actually .54 caliber. Case capacity turned out to be close to that of a .45 LC case with a 250 gr. bullet. Using similar loads of black and smokeless powders, the available energies were pretty close, given that tests with the .45 LC were done in a 7-1/2 bbl. revolver, whereas the carbine had a 22" tube. There was no rifle available in .45 LC, and I didn't want to buy one, and borrowing one wouldn't work as I was gluing strain gages to the barrels for pressure tests.

[ndnchf]

w44wcf - sorry it took so long, but I finally got to the range this afternoon.  I fired 10 rounds of my .56-50 across the chrono with my M1871 Springfield Spencer rifle. 




The load was:

.50-70 brass cut down to 1.356"
43gr by weight of Goex 2f (about 45gr by volumn)
Federal LR primer
Rapine 350 bullet, 20:1, weight 350
SPG lube

Velocities were as follows:

1103
1092
1094
1082
1052
1070
1085
1080
1074
1095

I'm sure I could get higher velocities out of Swiss or Old E, but this is the same load that shoots so well in it.  I tired both of the fancy powders, but neither was as accurate as Goex 2F in this rifle.

[dusty texian]

ndnchf, the only thing I would do with that load is make more of them. That is some fine shooting Pard.Great pic. and rifle. ,,,DT

[ndnchf]

Thanks Dusty. I was fortunate to find a great shooting load without too much effort. Its a heavy rifle which makes recoil very mild and  lot of fun to shoot.

[w44wcf]

Steve,
Thank you for the loading data!  Your load averages 1,083 f.p.s. - add another 10 f.p.s. or so for the distance to the chrono screens = 1,093 f.p.s. muzzle velocity.  That velocity nestles right in between the .56-45 and .50-54 data.

Nice shooting!  

w44wcf

[w44wcf]

One thing you need to take into account is the Relative Sectional Densities of the different bullets being used in different cartridges. Relative Sectional Density (RSD) is the bullet weight in grains divided by 7000 gr/lb, divided by the square of the bullet diameter.  For example a 250 gr. .45 bullet has an RSD of .175.  An equivalent .515" diameter bullet would weigh 325 gr.

Your 330 gr .45 cal. bullet has an RSD of .231, whereas a 350 gr .54 cal. bullet has an RSD of only.171.  Using the same powder charge for the "lighter" .54 cal. bullet will result in .171/.231 = .74. No, that's not the velocity that will result; it's the resultant energy.  Let's say the 330 gr .45 has a MV of 1250 ft/sec.  The muzzle energy comes out to 1145 ft-lbs.  Multiply that by .74 and you come out with 847 ft-lbs. Calculating the resultant MV, you wind up with 1043 ft/sec.

I don't have a .56-50, but some years ago I ran tests on a .56-56 using cutdown .50-70 brass and 411 gr bullets. The bullet diameters are actually .54 caliber. Case capacity turned out to be close to that of a .45 LC case with a 250 gr. bullet. Using similar loads of black and smokeless powders, the available energies were pretty close, given that tests with the .45 LC were done in a 7-1/2 bbl. revolver, whereas the carbine had a 22" tube. There was no rifle available in .45 LC, and I didn't want to buy one, and borrowing one wouldn't work as I was gluing strain gages to the barrels for pressure tests.

Trailrider,
Thank you for the interesting calculations.  It comes very close to mine and ndchf's actual data (updated 1st post).

w44wcf

[El Supremo]

Thanks for the great work: 
If you would, please measure the approximate twist in that 1871 and let is know.  It will help me resolve an issue involving lighter bullets in the 320 grain range that are approximately .714" long. 

One fascinating tidbit from "Snakeeater" recounts that the essential requirement for a rifle/carbine in the CW era was its ability to bring down a HORSE, head-on.  The 44 bore was inferior to the 50 in this regard.
Thanks. 
Kevin Tinny

[Herbert]

The 1871 Sprinfield Burncide Spencer uses the Sprinfield 1868 50-70 barrel with a twist of one in forty two inches

[ndnchf]

Thanks for the great work: 
If you would, please measure the approximate twist in that 1871 and let is know.  It will help me resolve an issue involving lighter bullets in the 320 grain range that are approximately .714" long.  Thanks. 
Kevin Tinny

El Supremo - As Herbert stated, the twist is 1-42".  These rifles were made up by Springfield Armory in 1871 using model 1865 Spencer carbine actions and buttstocks.  It uses a M1868 trapdoor barrel fitted to the Spencer action.  If you are interested, I've chronicled my load development here:

http://www.cascity.com/forumhall/index.php/topic,49533.0.html

[El Supremo]

Many thanks, NDNCHF and Herbert:
So many share loads, but omit the bullet length and rifling twist info. 

It seems that some early breech loading cartridges used bullets in twists that were too slow.  Your twist seems much better than in some earlier Spencers.  Twists of around 45" with velocities in the 1100fps range fit bullets around 1.5 to 2.0 calibers long.  It took British rifle makers a long time to determine and apply optimum twist rates.  Some of their mistakes flowed from using one-caliber long bullet stabilizing  ball twists in early bullet rifles.  I spent a lot of time learning that it is very unlikely that BP velocities can be increased enough to correct an unstable bullet at normal ranges.  As little as 4" of twist variation can work wonders in our era BP ctg's.  If a bullet is producing "wiped/oval" holes in the target at reasonable velocities, the simplest solution is to make 1/8 caliber changes in bullet length.  I've seen this method change mediocre rifles into consistently impressive ones. 

Seems interesting that Burnside 1865 56-50 Spencers AND the 1870's Belgian version had 24" twists.
Respectfully,
Kevin Tinny

[w44wcf]

El Supremo,
Interesting post. Thank you.

The test rifle I used to test the .56-46 ballistics has a 1 in 38 inch twist (.45 Colt Marlin Cowboy). The test bullet was .90" long (Lyman 457122) .

At the 45 gr. b.p. velocity of 1,183 f.p.s., the bullet holes at 25 yards appeared to be fairly round.  But, previous testing at longer ranges with smokeless indicated that a velocity of at least 1,300 f.p.s. was required to completely stabilize that bullet in the 1/38" twist.

w44wcf

[El Supremo]

Couple other questions, please:
Any leading with the longer barrel?
Any blowby on case sides?

I have decades of GOEX experience, back to the mid-70's.  One thing:  The normal, lot-to-lot variation due to ingredients, etc was a total of 7%.  If we sifted the stuff to remove dust and undersized particles, the velocity extreme spread was usually halved.  Velocity variation was our nemesis past 100 yards.  35 -40 fps shift could cause a 3" vertical change at 200.  Eyes, relatively crude sights, a HEAVY trigger pull and a huge hammer fall  are challenges with this rifle.  My compliments on what you have achieved.  Your results will be my goal with an as yet unfired, mint 1865 rifle.  My fantasy is to see if Larry Romano could improvise a scope base to fit IN the existing sight base.  My eyes aren't up to irons anymore.
Very Respectfully,
Kevin Tinny