As I recall the Sierra loading manual describes the 85 gr HPBT as a long range varmint bullet that can be used on smaller deer with careful shot placement with good results. At the moment I am a thousand miles away from said manual so perhaps someone else can take a look.
Conversely, the 90 grn Sierra HPBT in .257 is described the same way in the Sierra manual. I have had good results with that bullet on deer in a .250 Savage with 1 in 14" model 99. Sierra customer service told me simply to drive the bullet at top velocities for best results.
I would not hesitate to use either premium 85 grn bullet for deer. Heavier but cheaper 95 and 100 grn C&C or poly-tip bullets have also given consistently good results for years.
