Piling Swivels

I was going over one of the SMLE "component" drawings last night and it contains TWO piling swivel styles:

"Piling Swivel A" is the usual "offset" style, like a sling swivel with a bit removed.

"Piling Swivel B" is symmetrical and narrower.

Both carry the note: "Not for Mounted Troops"

Any clues?

The narrow pattern became the standard for new rifles some time after WW1. You find them on No1 MkV, No1 MkVI, No4 Mk1 (trials), and on most batches of BSA commercials - such as the "Bahrain" No1s.

The narrow piling swivel was introduced in the '20s
Lithgows from around that time & up to 1941 also used the narrow piling swivel

Lithgow from 1926.

Thanks: I have never owned a rifle with a piling swivel, of any description, attached!!