Thanks Drew. Maybe it was a hit and miss thing with some of the marking. I know I had emailed the Birmingham Proof Master a few years back asking him about when the date mark stamping started re: post 1921, he said "in theory" the date marks were used starting in 1921. To me that meant maybe they were hit and miss until the new 1925-1954 Rules.

This is one of my other threads showing barrel flats 1904-1925 without the Max, Shot, Ounces, etc. Barrel Flat Markings

My understanding from the above UK Proof website link is that for Nitro Proof marking between 1896-1904, Max, Shot and Grains or combinations thereof were used. Between 1904-1925 only the load designation mark was used, ie: 1 1/8 or 1 1/4; Max, Shot or Grains were not used. Between 1925-1954 the load designation and ounce mark were used.

________
TC