I once saw a real life example of a .224-20MM cartridge. I chuckled, which is exactly the affect the owner who made it was looking to evoke. As to Weatherby's new-to-production 6.5-300 Wea Mag, and their Mark V rifles, I'm still baffled. It will be interesting to see how many rounds the barrel can deliver before going back for a re-barrel.
For me, I'll stand by my .22LR, .30-30 Win and .308 Wins all day, shooting for decades. Yes, I do have a Fibermark in .300 Wea Mag, and I have owned several other Wea Mags. Those can do damage enough for my likes. When my .300 Wea Mag goes south, it will be rebarrled as a .300 Win Mag. I suspect that even such treatments as Black Nitride will do little to prolong barrel-life in cartridges the likes of 6.5-.300 Wea Mags, etc. This is going to be interesting!
JMHO,
Geno