I just wanted to add the my earlier comments some additional notes from the day of the Krag, in the 1890s.
In the same place in the Infantry Drill Regulations of 1891 (and 1892) where instructions regarding volley firing is found, there was mention of sharpshooters also. They could fire at extended ranges if permitted by an officer. No mention, at least there, of what a sharpshooter was but I gather from other pages that the term merely referred to the better shots. In another place in the book, it says that officers may specifiy individual men to continue firing on the enemy when the others have been ordered to cease.
The Infantry Drill Regulations at the time (from the Civil War to the early part of the 20th century) were more than just parade ground instructions for marching but were for pretty much everything the infantry did. The regulations themselves (the 1891 edition) were largely written by the same man who wrote the 1867 edition, although he had died by 1891. They were officially the work of a board of officers, not all of whom were infantry. A quick reading shows that not a great deal had been changed in the previous 30 years but the breechloading repeaters did allow (and require) the infantry to make greater use of cover but battlefield movement was still essentially marching from one place to another.
Horses were still the prime movers during that time, too, and instructions were that for artillery during movement, the horses should be the target.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
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