Why the change from 56/56 to 56/50

[Cannonman1]

What was the reason for changing the caliber of the Spencer from the Civil War 56/56 to the smaller caliber and changing the rifling as well?? Seems like a waste to dollars and time. There were millions of rounds on hand for the 56/56 and it was a proven weapon.
The Sharps conversion makes total sense.. but the Spencer??? Anyone out there know the story?

[Two Flints]

Maybe these pages from the Marcot book will be of some help in answering your question??





Just a suggestion, but maybe you should purchase the Marcot book . . . lots of information about the Spencer.

Two Flints

[Cannonman1]

Looks like a great resource book and one I will definitely get.

Thanks

[Trailrider]

Part of the problem with the original No. 56 cartridge (aka .56-56, which was the dimensions of the case just in front of the rim and at the mouth) was that it utilized a heel bullet, lubricated outside the case, and was approximately .54 caliber. (Actual bullet diameter outside the case varied quite a bit from manufacturer to manufacturer!  By reducing the bullet diameter and the bore/groove diameter, Springfield Armory was able to use an inside (the case) lubed bullet, with a substantial crimp by the case mouth on the bullet, insuring the bullet would not be jostled loose and the lube wasn't likely to pick up dirt, being protected by the case.  Although called the .56-50, the barrel dimensions were: bore .50 caliber, groove diameter approximately .515".  Christopher Spencer thought the Springfield cartridge had too much crimp, and so designed a more bottlenecked case, but used the same bullet diameter. He called this the .56-52.  In reality, the .56-52 would chamber and shoot just fine in the .56-50 carbines.  Since these were all rimfire cartridges, they wouldn't be reloaded, and the .56-52 case fireforming to the chamber was no problem. As a matter of fact, all three cartridges would shoot in the older M1860 Spencers, if one could accept a little less accuracy. The .50 caliber bullets would generally upset to fit the larger M1860 Spencer barrels, although accuracy probably wasn't as good!  The Spencer sometimes had a reputation for excessive drift.  One wonders if this wasn't due to shooting the .56-50's in the .56-56 chambered guns? Army logistics being what it was in the post-CW Indian Wars campaigns, the newer ammo might have been issued to units that still had the M1860 carbines and also the M1860 rifles (3rd Infantry being the only doggie outfit West of the Mississippi armed with repeating rifles).

If you look at the sequence of cartridge development, the next step for Springfield was to lengthen the case, and change to a central fire design, but using the internally primed case design. This was, of course, too long to fit in the Spencer, but worked well in the Allyn-conversion breechloading Springfield .50-70 rifles, and subsequent models, including the Sharps conversions.

[Oregon Bill]

Two Flints, thanks for sharing those pages from the Marcot book, which it looks like I need a copy of!

[Oregon Bill]

On second thought, seeing that used copies start at $200 and up, I guess it will have to wait until I hit the lottery!

[treebeard]

On second thought, seeing that used copies start at $200 and up, I guess it will have to wait until I hit the lottery!

Wow— maybe i'll Take my first edition and put it in the safe deposit box for safe keeping!,

[major]

I have a first edition I would be willing to sell for $250 shipped the the 48.  t.schultz5@roadrunner.com

[Coal Creek Griff]

Before eBay dissolved Half.com, I had that book on my watch list. One popped up for (I think) $30 still wrapped in plastic. Oh, yes, I jumped on it. Maybe an eBay automatic search would turn one up eventually...

CC Griff

[Blair]

To answer the original question... it was cost!
Three wide groove rifling could be cut faster during manufacture than six narrower grooves.
Springfield designed the 56-50 and 56-46 for two reasons, 1. was save on costs of buying other makers ammo, 2. was in the hopes of standardizing the various small arms (carbines in particular) ammo they were having to provide the Army in the field. Also with the hope of modifying many arms already in service to the new ammo.

Hope this helps.
My best,
Blair
   

[DJ]

Somewhere I heard/read that part of the reason for the change is that 56-50 is ballistically superior to 56-56.  I have always wondered how significant the difference really is, especially with a barrel that is two inches shorter.  Anybody know for sure?

[Blair]

DJ,

All factors being equal (powder charge and bullet weight) a smaller dia. bullet would produce better ballistics. Less drag on the bullet while in flight. That is at least my take on the subject.

My best,
Blair

[DJ]

I get it that all else being equal, decreasing diameter of the bullet would increase ballistic coefficient and make the bullet shoot "flatter."  I also understand that shortening the barrel would make the initial velocity less, making the bullet shoot less flat.  The dimensional changes in the Spencer cartridge, and the amount the barrel was shortened, both seem rather small, and would not seem to justify the expense and "hassle" of retooling the production line and retrofitting existing rifles and carbines, along with adding a new and different caliber to the supply chain. 

However, my question perhaps sshould have been, how much of a role did the improved ballistics of the new Spencer cartridge play in the decision to change?  Or was the change driven by other considerations with the improved ballistics being merely a byproduct?  Shortening the barrel suggests that improved ballistics was not the main consideration.

--DJ

[Blair]

The best suggestion I still have to offer is cost to the US Gov.
In late 1864 to early 1865 wanted changes in the older Model 1860 Spencer's to meet these cost.
Smaller bore dia., slightly shorter barrel and fewer grooves equaled a slightly faster (note) "rate of twist" in the rifling. All of this could be done with the development and production of a "new" model arm.
This is why the US gov. brought the Burnside Co. into a contract to produce Spencer Carbines to help supply the arms needed by the Army.
Other Gov. changes caused a slow down in not only production rate, but in dates of delivery for not only Bureside contract but for Spencer's "new" models as well.
Burnside's contract as for 30,500 + arms was not filled until October of 1865. That makes for a lot of unissued arms for them alone.

I hope this info helps?
My best,
Blair

[Cannonman1]

You can actually fire a 56/50 cartridge in a 56/56 rifle can't you??  I know the accuracy would not be the best..

[Rim fire]

Yes you can.