I have not used many 338 bullets. I had a couple 338 Win Mags but they didn't see much use as I didn't do much hunting right then that required that type of rifle. I would have thought that any 338 bullet should penetrate the shoulder of a whitetail. I do however have no reason to doubt his story. The SD of that bullet is over 250. I quess I would stay with 250 grainers or go to the X bullet if I wanted a light weight bullet.