Re: 1-10 twist 300 win mag
I guess the better question is what do you want to do with your 10twist 300win mag. Any bullet from 150gr to 240 gr can be used.
For hunting, I would suggest the 165gr as a great compromise. For long range shooting, the 155gr Amax or any of the other Matchkings.
As to what will shoot best in your gun. only experimentation will solve that. So if you have more details about what you want to accomplish, let us know.