Jani,

I think you have to register it as a 6,5-52R, if this is required for acquiring the S&B cartridges or for other purposes. Now the inconsistency on what the barrel flat says and the current cartridge denomination is due to a diference between measurement on land and on grove IMO. Has the local proof house a say on this? Here in Chile, also a CIP member, they are quite amenable; they noticed the inconsistency in my case and, after proofing, accepted this drilling to be registered as a 12/12/25-35Win gun.