You’re partially right, but mostly incorrect. All the calibers you’re thinking of were designed 70 plus years ago. You can’t take an off the shelf .243 and decide you want to shoot 120 grain bullets in it without modifying everything. I had a 600 Remington in .243 that wouldn’t stabilize the 105 grain bullets due to slow twist rate, so was stuck with 87-90 grain bullets for it. With the new offerings they can optimize magazines, twist, and chambers but then it’s new. I welcome the new offerings because manufacturers are finally giving us more of what we have been asking them to build. Life is good!If it is the brain child of an American Rifle company then the 6.8 western is a no-go. Them basturds haven't been able to produce rifles with correct twist rates for the 243, 270, 280, 7RM, 7mm-08....... for years now. If they haven't figured out twist rates, why the hell would I want some cartridge they came up with? Nope, they are not very bright. Hornady looks like a frigging marketing and ammo genius just because they put correct twist rates in their ammo specs when they develop their rounds. No, don't want some round created by a mismanaged company that doesn't listen to customers.