I used my .243 for years with one shot kills on all broadside deer. My wife and sister has been using it for the last couple of years for one shot kills on large mule deer/whitetails. Last year, same gun, 2 deer. 3x4 mule deer, 178 yds one shot drt bullet penetrated the shoulder spine and off shoulder. Recovered bullet weighed 51 grains(100grn gameking). My wife on the same day; one shot 40 yds double lung no bones hit, deer left a blood trail for about 150 yds. Difference; one hit bone and penetrated on an unaware mule deer, the other only hit lungs on a very nervous whitetail. Same results ONE SHOT KILLS. This year they teamed up again with my little
243 both one shot kills (again) My sister at about 150 yds, 3pt mule deer and my wife at 327 yds on a whitetail. The mule deer went about 75 yds on a rear quartering shot penetrating completely through both lungs same with the whitetail, it went about 30 yds on a broadside shot. Try to stay with the 100 grain gamekings, they have worked for me every single time.