T 7,.... I don't have a .50 cal. rifle to play with, or any .50 cal. balls to weigh, so,... I bet yore "right" 'bout the 50 cal. "weight".
Thet be'n said,.... roundballs "kill out of proportion to printed-ballistics thet use jackets, high velocity, weight, and etc. to establish "ballistics-standards" for "kill'n".
Roundballs do "shed velocity" rather quickly past 100 yards, but I ain't seen nobuddy reccomend'n shoot'n big-game animals with roundball, past 100 yards.
I shoot, .58's, .62's, and .75's nowadays (the .58 is my personal favorite),..... but, I have take'n several mule deer with .45 cal. "roundballs" years ago,... and a couple of'em were near 75 yard shots. "None" required a second shot, "none" were wounded and lost,.... and I believe ALL were killed "more by shot-placement",.... then "ball-weight"!!
A lot of the "hype" one reads today, is from companys sell'n ther "special bullets",..... in other words,.... for them it's a "money game".