I have a 1939 Carcano cavalry carbine that I have struggled with primers being partially pushed out of the primer pockets, even with mild cast loads. I wound up neck sizing only, and after a few firings I measured my cases. From the base to the shoulder measures 1.65”, and the distance from base to the bottom of the neck is 1.80”. The case diagrams on Load Data shows that I should have 1.62” and 1.77”. Also, the case capacity is just a little higher than standard Carcano cases; 51 gr H2O vs 49 gr. I know this isn’t a lot, but they all match up almost identically to 6.5x54 M-S.
On Wikipedia (I know sometimes it isn’t always 100% reliable) it says that during WW-II some captured 6.5 Carcanos were converted to 6.5x54 M-S for use by the Greek army. I know it would be almost impossible to track down the history of this carbine to check that fact, but what do you guys think? Was it more likely a conversion, or just a head space issue? In either case, would I benefit any from buying a 6.5 x 54 sizing die to do my sizing?