I got a few boxes of the Brown Bear 203's around... I have 3 Mosins but the one I would (and have) taken hunting is my '43 IZH ex-sniper 91. That one is pretty accurate, iron sights and all and it seems to like those rounds. I don't reload for that caliber and have never slugged the barrel on it (yet). Testing at the local range told me it was pretty good with those at 100 yards and the Winchester stuff, can't recall the weight of those.
I haven't bagged anything with mine but went out a couple of years ago for Wisconsins late season. Didn't see anything. I was wondering about the last time that weapon had been out in the snow with bad intent... who knows, maybe a woman carried that thing in their Great Patriotic War...