So you're shooting a 308.
You didn't say what bullet weight or the shot angle.
120 yards with 308 - couple of options:
destroyed heart (no pump, no flow),
went in rib and out paunch (guts plugged exit hole),
or it went in and stayed in, maybe up under skin on far side.
I doubt it was a ribs only dbl lung shot without full penetration and no blood.
Can only change a couple things - shot placement, bullet construction, bullet weight, bullet speed.
Shot placement - high shoulder shot or at least take out 1 shoulder. They don't go far like that - except if the gun is a 243 and 100 gr factory ammo. Don't ever shoot a deer in the shoulder with 243.
Bullet construction - Nosler partition is probably the best hunting bullet ever.
Coppers are possible but I'm old and don't need to go down that road.
My fav bullet is the Sierra Pro Hunter and it's a shame they aren't making them right now.
The Ballistic tip you mention is supposed to be a good deer dropper, never tried em.
Hornady Interlock is readily available and seems to be a relatively tough bullet.
There are plenty more. Core Lokt is a proven killer.
Bump up the bullet weight - a 165 or 180 gr will carry more energy than a 150.
Bump up the velocity if possible. Speed kills cause it disrupts more things upon impact.
