When a min muzzle velocity of 2450 fps was introduced in Scotland it effectively made the 6.5x54ms redundant as it does nt hit that velocity with its standard 160gn bullet. Our licensing authorities did nt really understand home loading and many of these old rifles were traded in for 270's etc. Se were re chambered to the 6.5x55 which does meet min velocity requirements, and any rechambering would require proofing, hence new proof marks.