My bet is that if you'd shot him with the 150-grain "standard" Partition the results would have been very similar. This is based on shooting similar animals with similar Partitions (both Gold and standard) and finding quite a few a long way from the entrance hole.
Two standard Partitions that come to mind are a pronghorn I shot at 300 yards with a 100-grain .25 caliber started at 3200 fps or so. The buck whirled just as I shot, to challenge a buck coming up behind him, and the bullet hit the right hip joint. The buck dropped and died right there, due to the little Partition going all the way through him to the left shoulder, where I found it.
Another was a mule deer buck about the same size as your blacktail. Shot him at about 35 yards with a 140-grain Partition at 2900 fps from a 7x57, right at the base of the neck, hitting the bottom of the spine. He also dropped at the shot, and though I looked for the bullet while field-dressing couldn't find it, though did trace the path through the lungs and diaphragm. Assumed it ended up in the gut-pile, but somewhat later bit into a round steak and found the expanded bullet, which had obviously gone lengthwise through the buck into the ham.
As I posted on another thread, I never could tell any difference in penetration or anything else between the Partition Gold and the old standby, except a little more retained weight for the Gold on the rare occasions either was recovered.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
