No hands on experience. But have read a couple different accounts of chambering issues with loading .358 diameter bullets in the 350 legend. Some say they just won't chamber other accounts have the round as being a crush fit upon bolt lockup causing excessive pressure. Easiest any safest route seems to be resizing .358 rifle bullets. Sized to .356 and you are good to go. Seems the way to go opens up a wide selection of bullets, chamber stays in spec still allowing factory ammo use.
Winchester really screwed this up. Could of been perfect if they would of based it on a .223 case and used .358 bullets. They for whatever reasons had tweak things just enough to make it undesirable to the handloader market.
I was all excited when this was announced. I am a 35 caliber nut. Have a very larger horde of bullets. Got countless 223 cases as well. Figured a set of dies and I would be all set for an AR with a little extra thump that I could shoot cheaper than even the cheapest 223. Having the buy the brass and the extra step of resizing the bullets killed that idea.
Here is some "official" info on loading the 350 legend. Have read other online forum accounts that are along the same lines.
350 Legend