I have some S&B 196gr 8mm ball on hand I won't shoot.

Can I pull the S&B bullet, use the original powder charge, and safely replace the 196gr ball bullet with a 150gr hunting bullet?

Though it would probably be safe, why deal with the unknowns just to save a little powder? You can load about 150 of those cartridges with only one pound of powder.

Perfectly safe; I would do it if I thought I needed to. Here, that pound of powder will cost close to thirty bucks, if you can find what you want.

Safe I guess. I've done it.

I've done it more than a few times, never a problem.

The load will not push the bullet to the max by any means,but would be safe to shoot.

I would do it without hesitation.
I would go a step further and pull all the bullets and dump all the powder in a container then weigh each charge only because I am wired that way and would assume that I would weigh the powder more accurately than mass produced ammo thereby convincing myself it would be more accurate!

It will be safe and if it is a modern European load, interpolation indicates that you might get 2600 fps.out of it. That would be some where between 30-30 and .300 Savage performance. That's not all bad for deer hunting. roger

Thanks to everyone who responded. Its good to know this is a safe trade.

Also good with a 185 Remington CL. Also good with a 200 Speer. Have done both with 198 Portuguese Ball which is about the most "max" mil load around.
Yes you should not trust anything on the internet when it comes reloading...

I would pull all the bullets and dump the powder into a measure. Divide the total weight of the powder by the number of cartridges emptied to calculate the average and use that for the powder charge for the new rounds.

Can I assume you're using a neck sizer to restore neck tension?