I saw three consecutive 100 grain TSXs fail to expand on on a bull elk from a 25-06. I would never trust a copper bullet that small again. Never had any problems with 7mm and bigger. Smaller ones are not as reliable.
There are better bullets for hunting coues deer with a 257. I have seen quite a few killed by Ballistic tips with good results as far as 550 yards from a 25-06.
look at the ACP bullets, they do expand in the smaller calibers
I use them in .22, 7mm and .35
they are available in different hardness compounds to suit different velocities and animals
