Need help with Lend Lease M1 rifle import letter

[RCS]

Photos show my Lend lease M1 rifle, there is a lend Lease Code and each letter
that is stamped near the barrel date indicates the year of import. I can not make
out the letter code - any help would be appreciated.

1963 - O 1962 - N 1961- M 1960 - L 1959 - K 1958 - J 1957 - H these are
the last codes477524775347754

[Johnny P]

The date of proofing is in the left quadrant of the crossed scepters (B for Birmingham in the right quadrant, and number in bottom quadrant for inspector. Can't make out the letter in your photo.

This one was proofed in 1955, showing an F in the left quadrant.

https://i.postimg.cc/pTRd6pp4/BHP.jpg

[lyman]

blew it up on my lap top and it is truly hard to read,

RCS, got a better pic?

[RCS]

I was just checking it with very strong magnification and still can not be certain; I think it has to be
a J or K ?