ID Please - .45 cal bullet (see photo and measurements)

[Sparkle]

Hey Guys: New member, great forum.
A friend dug six bullets like this one near Fort Meade South Dakota (established 1878) with the help of a metal detector.
The bullet measures .457 diameter.  Weight 374 grains.  Length 1.1 inches.  It has a conical nose, cannelure groved (not rings), and a concave base.
Since it was found near the cavalry fort, I assumed it was a 45-70 Government or a 45 pistol bullet.  But everything I read says the weight is wrong for either.  Most 45-70 Government were 405 or 500 grains, and the pistol bullet was usually 250 grains.
Any ideas what this might be? 
Do you think it was used in a muzzleloader, or in a metallic cartridge? 
Pistol or rifle?
 ---Sparkle in Minnesota

[acwbullets]

Sparkle,

That is a .45/70 bullet. The weight may be off due to the type of cartridge. The earlier versions were much heavier and were for the copper cartridge that was rimfire or centerfire. You may also want to look into the .45/70 carbine bullet weights as well as those used later in the tinned cartridges. Being that you found it close to the cavalry fort it may be for the carbine cartridge. All of the dimensions of these bullets are listed in the Memoranda No. 21 I believe. These are tough books to get but some of them are currently being reprinted.

[Sparkle]

Awesone.  Thank you for the quick and authorative reply!