At the risk of being shot down in flames I don't think there is such a thing as an 1864. I know of 3 enfield "Pattern 53" muskets all of which were rifled and all .58 caliber.

The original was introduced in 1853 and had 3 barrel bands. The later 1858 (Naval pattern) was slightly shorter and had just 2 barrel bands. Finally a much shortened cavalry carbine known as the musketoon was introduced in 1861.

All of these were originally muzzle loading percussion cap muskets. Many were later converted to breech loaders using a conversion invented by Jacob Snider.

There were target variants in the form of a Volunteer rifle and a military target rifle, both of these were made in .451 caliber.

An internet search for Enfield followed by 1853, 1858 or 1861 will all prove fruitful, including details of the repro's made by Parker Hale from 1970 onwards. Also search for Enfield Snider conversion.