Sorry Wes, I missed it in the verbiage in your 1st post. I'm consumed with these weapon's puzzle. Don't dig too deep or you'll develop a habit also. Without looking I think "f" was 1927. It's a linear progression date code via the alphabet beginning in 1922 with "a". The date code is the "f" right below the "Crown" over "R" denoting proof of a rifled tube.

Kind Regards,

Raimey
rse