There were a handful of the Soviet-era Running Boar rifles released 20 or so years ago, n this weird 6.5x54R. Local fellow bought a couple and couldn't locate ammo, so we went about locating some out in the shop.
I was lucky in that I had 6 rounds of factory original ammo which had been sold to me as 6.5 Arisaka (which I knew in an instant it wasn't), so I gave him 2 and we set about duplicating them. Brass is 7.62x54R, of course. You can neck down the tops of the cases with a 6.5x55 FL die if you chuck the die into a lathe and turn off about the bottom inch of the die. The (remaining) top will neck your brass very nicely.
If you are starting off with FIRED 7.62x54R brass, run them through a 7.62x54R full-length die with the expander button removed. That will resize the critical web area of the brass AND get a head-start on your converting the front ends.
Once our brass is converted, you necksize only, which is no great hardship if you have only the one rifle. This can be a wonderfully-accurate cartridge.
Original rounds DO have the wide rims, big Berdan primers and dished rims of the military rounds, but the ones I have are BRASS cases. Factory slug is a FMJ. I haven't pulled a round down to determine what's inside it; suppose I should do that some day.
Last I heard, he was loading with H-414 and Norma 139 HPBTM slugs and making tiny little groups.
But that's an easy way to convert the cartridges. Much cheaper than splurging 150 clams for a set of custom dies.
Hope this helps.
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