I am extremely skeptical of the above chart's validity.

First off, what are the barrel lengths used for calculation? 300blk uses a saami of 16" where most other calibers use 24". Why would anyone assume those numbers are directly comparable?

Second, 30HRT is a wildcat. There is NO SPEC for it, so putting it in a chart along with factory 300blk is questionable. Same for the 223 77gr SMK, is that someone's handload or mk262?

I'm coming off as a defender of 300blk I know, but that's not it. I wouldn't trust those 30-30 numbers, I don't believe 6.8 retains THAT much more energy than 30-30 or 223, etc.

That chart is extremely suspect.