I shot an 06 for many years,I would not recomend anything lighter than a 140gr partition type bullet.In my opinion you will not gain anything with the higher velocity of the lighter bullet,the energy that the heavier bullet will deliver on impact will give you a whole lot more stopping power and if you want to put deer down quik that is very important.

I view this question, as one of "sectional density", the ability of a bullet to penetrate the animals vital organs in the kill zone.

I fear that a .30 caliber bullet would not have enough penetration and also it would more than likely be to fragile on even deer size animals. I suspect that abe driven that fast would cause the jacket to turn inside out or just fragment altogether.

The 125gr 30 cal bullets that I know of are NOT designed for big game hunting. It is light for caliber. Stick to the bullets of the caliber that were designed for the purpose. If you want to shoot a lighter bullet. Use a smaller caliber bullet that was designed for big game.

Whether it be a 22 center fire or a 338. The light for caliber bullets are typically, NOT designed for big game hunting.

Go with a 150. If you're hunting bigger mulies or deer and the weather forecast calls for a breezy day, I'd say go with the 165. The 180 might be a bit too heavy, it may not expand much in a deer, which is a relatively light animal.

I'm willing to bet for a solid bullet in 125 gr it won't make much difference, if you use a ballistic tip however, while a well placed shot will still work fine if much penetration is required the bullet will not perform adequately Z

Don't take any chances. Go with a 150.

Generally Speaking:

Using bullets with Sectional Densities higher than .250 is usually best for light-skinned game and .270 or larger for heavy boned animals.

I would be more concerned about your barrel being able to stabilize a 125 grain 30-06 bullet (how it groups). If it is stable, then it is enough fire power in my opinion.

It works a bit differently from like a .257 caliber bullet in the same weight-class. If you managed to put it through soft flesh and into the chest cavity, it would result in a kill, but if you hit bone, you're out of luck. It's just not a big game bullet.

i use a 150 gr. nolser partition/accubond for deer,elk and antelope never had a problem,I dont think you can go wrong with a 150 for anything here in my state.