If you want to extend range there are a near endless amount of variables from projectile construction, to B.C., to load, to rifle twist rate ( to match the bullet weight), and on and on..
Most simply put, a heavier bullet is how you stay effective at putting down animals as you extend the range. 150 grains is a relatively light -06 loading, you may be better suited stepping up to 180+.
Nowadays there are some impressive penetrating rounds on that light end, like the TTSX, winchester power core, GMX - Which are monolithic (Not core and jacket, like traditional bullets). Nosler partition and XP3 are sweet also (but are not mono).
Whether any of this is necessary or not is partly what/where your comfort and skill level is at: where does it become too far and with too many variables (wind, elevation, temperature) for an ethical and reasonable shot.