A 150 grain bullet coming out of a 06 would be fine for deer,antelope and black bear and I would draw the line there. The sectional density is simply not high enough for reliable penetration on bigger animals and the starting velocity is not enough to give good results at extended ranges. You could use a 150 grain failsafe coming out of a 300 win mag driven at higher velocity on elk ..some people do because of the recoil factor and the fact the bullet sheds very little weight . I still prefer using a high sectional density bullet. Now in a 7 Rem mag or STW or something along those lines a 150 grain partition/premium bullets will work on bigger game because you have same or close to the same sectional density as a 180 grain 30 caliber and plenty of velocity to take advantage of it at extended ranges.