Gunner500: I have used those "old style" 100 grain Nosler Partitions on Deer and Antelope in the past and they worked rather well.
IF... that Featherweight in 243 is "really nice" like you mentioned then get this urge to Hunt with it out of your system ASAP and find an old Remington 700 in 243 to use up those old Noslers in.
I have three Featherweights in caliber 243 Winchester (including one "Gopher Special") and in my opinion they are just way to valuable to take afield and Hunt with.
But to each his own and I hope your 243 shoots well for you and you don't ding it up much while sighting it in and Hunting with it.
Enjoy.
Hold into the wind
VarmintGuy