Shooty stuff

"There are very few animals on ANY continent that cannot be readily dispatched with a stoutly constructed, 165 grain, 30 caliber bullet impacting the heart-lungs area at 2400 feet per second."

"The ideal elk cartridge would launch a wood-stove at 2200 feet per second."  -Elmer Keith

From the perspective of sectional density, what is the equivalent of a 165 grain, .308 bullet?

.243 (6mm) ... 103 grains
.25.... 115 grains
.264 (6.5mm)... 121 grains
.277 (6.8mm)... 133 grains
.284 (7mm).... 140 grains
.323 (8mm).... 181 grains
.338 .... 199 grains

Differences between .300 Blackout and Russian 7.62X39mm

Average muzzle velocity for the 7.62X39mm Russian is 2360 feet per second for the 125 grain soft point.  Data taken from Hodgdon Reloading website.

Average muzzle velocity for the .300 Blackout is 2125 feet per second or about 20% less energy.  Note, subsonic load and "alias powder" data were omitted from these calculations.

It is worth noting that the .300 Blackout data is taken with a 16" barrel while the Russian 7.62X39mm data is taken with a 24" barrel.