Jimbob,
I can tell you this about wrong bullets...
Some years ago pop was wanting a different bullet after having a couple 180G spitzer bullets fail to expand on deer. He bought a box of Speer 150G FN, meant for the 30-30. His thinking was if I dont load them to max and just a little past 30-30 ballistics, I should be fine... SO He loaded them up in his 308 but not at a max loading.
For the next two years he ALMOST lost every deer he shot.
Late in the first year, pop watched a fair buck rubbing his horns in thick laurels. He could see the rack, and neck but no vitals. After about 30 minutes he had his shot. Some what screened with laurel leaves, but it was not far so he took the shot. NO effect... deer kept doing its thing with the tree... He shot again. this time the deer stopped for a instant and continued but more violently. He moved just a bit and found an opening and shot and dropped the deer. What had happened was those bullets had hit the laurels and came apart. That deers side was bleeding profusely. Almost his whole side!!!!
When we skinned it there was 6-8 small cuts just they the skin and the jackets that caused them where right there to tell the tale. He simply said to him self, I cannot shoot thru anything with this bullet. (Bad call)
Then in that second season, the biggest horned buck he had ever seen in the woods was in front of him. He only had a straight on shot. But no worries, he has shot many deer same place. The distance is about 60 yards wide open, bang... flop goes the deer. Pop looks down to get his footing to get off the tree he was on and looks up to see the deer crashing into the laurels. No worries he was not "doing well" and would not go far.... NOT SO.. we looked for TWO DAYS!! We called in family, friends and neighbors to help look. We made a grid walked almost touching each other in a line a hundred yards long for miles... NOTHING!!!
A week later back at home I pot pop up in one of my stands and made a little circle around him... Sure enough a little 8 Pt came out and pop shot him. This time broad side, down when the deer and again up he came! Pop was able to hit him again anchoring him. Neither bullet exited and when we butchered it there was shrapnel remaining...
Long story, short... The Speer 30 cal made for the 30-30 is not well suited for the 308 at 308 velocities for use on deer...
Now I know you asked about the 170 RN Hornady bullet and not the Speer of my stories. But my point is its a 30-30 bullet, not a 308 bullet. Now I do very mcuh like the Hornady bullets, I use the 170 with good success in my 30-30.... But, it will stay with my 30-30 thank you very much!
After that experience, Pop and I switched to another Speer bullet. The 165G RN bullet. Expressly designed for the 30/06,308,300 Savage. Unfortunately it is now discontinued. I was lucky enough to secure a life's supply (12 boxes) before it was gone.
What I would recommend to you would be don't tempt fate, we KNOW the 170G Hornady is a 30-30 bullet. YES some people use it and have had luck with it in bigger cases. I in no way want to slight them for it. But the fact is it is STILL a 30-30 bullet. Designed for the 30-30 velocities.
Please consider using a Sierra, Speer or Hornady 180G RN designed for the 308 cartridge and do not worry!!! Pop lost the biggest racked buck he will ever likely see, because of a stupid decision. Please at least consider my suggestion and remember my story. I for one will never forget it!
Merry Christmas,
CW
EDIT:
Something to remember when choosing a bullet. ANYTHING of 170 Grains is designed for the 30 Rem/ 30-30 Winchester vel range. That's 2200fps at the TOP end. The 150's are harder to differentiate, but generally speaking if its a FP or RN with a canalure, its a 30 Rem/30-30 Win bullet.