You are right jack, I must have misheard about barrett.

I found this article:

https://sofrep.com/news/socom-wants-...-6-5mm-rounds/

and it seems to agree with your statement of 6.5 outranging 308 by 33% for practical accuracy. It took a lot to get my Savage MSR10 to run right, but now that it does; I see why a 6.5 gasser would be a great people killer. With an 18" barrel my 140gr FMJ (0.53 G1 2550 FPS) is ballistically equivalent to m118LR from a full 24" tube. And softer to shoot, which means better self spotting.