Hello:
For years, I wondered about a detailed parts list for original Spencer's.
Couldn't find one in Marcot. Then Arizona Trooper kindly suggested I look in the orig Patent.
That Patent # 27,393 of Mar 6, 1860, for the first prototype, not the Model 1860, is partially shown in Marcot, 2nd Ed. on page 14.
I downloaded the entire, three-page Patent and within its written specifications are terms for a few parts.
The spring loaded, narrow, finger-like part that lays on the top of the upper block is called a "tongue" by Mr. Spencer.
A modern term for it is Armisport's "cartridge feed guide lever".
Marcot uses "cartridge guide" on 2nd Ed. pages 107 and 136.
Patent 58,738A of Oct. 9, 1966 refers to the cutoff on top of the block and uses the term "cartridge guide with its swinging stop attached".
Parts dealers often refer to it as "cartridge keeper/cartridge guide/cartridge follower".
Because Spencer's original Patent did not include the two thin upward projections on the top, forward portion of the lower block, I have no official terms for them. Thanks.
El Supremo/Kevin Tinny