I agree. From everything I have read going all the way back to WDM Bell to modern testing, the 6.5mm seems the best compromise for size and weight. It performs about as well as a .30 yet can be made with a higher ballistic coefficient and still not have severe recoil.
I remember when I was a kid back in the 60’s. I ordered a Swedish Mauser through the mail and also a hundred rounds of those old 160 grain round nose military surplus rounds. Those bullets were extremely long and would penetrate the largest trees I could find. Actually astounded people including me when they would see the things penetrate a four foot thick tree.
Yup. Those 160gr 6.5mm pills have an incredible sectional density.
This, BTW, is why the bullet that killed JFK was no “magic” bullet. It was just typical of what a 6.5mm 160gr pill could do — keep going, and going, and going...