Thanks Mike.
Those old Hornady as well as the Remington 270gr RNSP where a favorite when I still maintained a H&H. These old cup and core bullets are just wonderful for these moderate loadings. While I load and use super high performance high BC bullets for the Prairie, i do love these sensible classical chamberings and there heavy for caliber (conventionally constructed) bullets at that magic 2200 to 2400fps. I think I read and commented on a Blog pretaining to this....;)
With a few trimmed .223 cases and a swage you could make some 320's........

I had a x57mm that was proofed for the 270gr, odd that the "smaller" NE case is proofed for the 320gr. The "small" case 375's handle the 300's and 350's very well in my tests. While not a classic persay, I have a hankering for a Whelen. Mainly for the ease of feeding it.