Here's a pic of the barrel flats on my D4, Grade 3, Parker. My understanding is that the "D" is for damascus, the "4" above it is the number of blades of damascus, (a D with a 3 above it would be a 3 blade damascus set of bbls.), the "3" way to the right is the Grade number (DH in this case) and the 4-1 is the unstruck barrel weight. I'm unclear on what the "C" on the barrel flats and also between the lugs is for, any ideas?

Wild Skies
Since 1951