Since my first post, I've researched the .300 Whisper in more detail and also received advice from other hunting pals. I'm now considering the purchase of a new Alexander Arms in 6.5 Grendel. Meets the criteria for low recoil and ability to kill thin skinned animals, like white tails. The long range ballistics are also quite impressive. Think I'll leave my S&W as a .223.
Good call, 6.5 Grendel is a great round. You should have more reach with that cartridge and more retained energy past 200 yards.
You wouldn't happen to have any info regarding ballistics.
300 AAC BLACKOUT (300BLK)