Winchester and wolf both make brass cased boxer primed 180 grain rounds in 7.62 by 54R.
IIRC, you can use a different size of boxer primer in a berdan shell, and ream/drill the pocket to dimension and make the center flash hole required for the berdan primer.
This is for the steel cased stuff. I don't think I'd mess around with converting a brass case with a berdan primer.
Also, to resize the steel cases, you need F*** tons of lube, and they need to be annealed. It helps to use carbide dies since the steel-on-steel will wear the die out like yesterday's toilet paper.
I have yet to produce functional ammunition, but will report back as I progress. Don't go buying a ton of steel cased, berdan primed ammo and expect to reload it just because of something I recall from a conversation a year ago. THAT guy might have been full of something other than knowledge.
However, it's worth a shot. I'm not changing the headspace dimensions, nor will I seat a primer in a pocket that is too large or too small, since I fear overpressures (have experience with amateur rocketry - I know how rapidly pressure can build up with energetic propellants).
But, FWIW, winchester does make some really nice ammo for the Mosins at about a buck a round. Not bad when you consider you can reload the snot out of it. Not great when 20 rounds of romanian crap costs 6 bucks.