The truth is, there is every probability that a 125 or so grain .311 bullet started at 2300 fps WON'T penetrate to the same depth as a 170 grain .308 launched at the same velocity as a 30 WCF.
But, if we estimate the width of a whitetail deer is say, 14 inches, and the Russian penetrates 14.5", while the 30-30 penetrates 20", what difference does it make? (With the caveat that the hunter shooting the Russian is willing to wait for a shot to the armpit.)
