I've killed a fair number of deer with this specific bullet, including 2 this season 2021 production bullets with a .300 Savage and a slightly lower (estimated) velocity than yours. Expansion was as I would have expected from any generic soft point. "Good" damage and a pass through without any long quartering angle or heavy bone.
I have had exactly one failure with a Hornady bullet over the years, and it was on a shot similar to your boiler room shot. Bullet passed through high lung area without hitting any ribs, and didn't appear to expand. The lungs were also barely impacted. As best as I can figure, the bullet hit just as the lungs were at minimum inflation and simply didn't impact enough tissue to expand fully. Exit hole was slightly larger than entrance. This was with a 174 RN in 7,62x54R caliber.
Try putting them through some plastic jugs full of water and see what happens.
I typically don't see a lot of exit hole on neck shots. The bullet seems to shed petals in the heavy muscle and bone there, expending most of it's energy inside and driving a relatively narrow core out the back. I get this effect with everything from NP to Speer GS, Hornady IL, Hornady SST, and Win PP and Speer Hot Core from .300Sav to .280 Rem including some relatively light for caliber bullets in the .280. I favor the neck shot when practical, and the majority of the deer I've killed have been with this shot placement.