I only pointed out the cost difference in the bullets??
The fact that you compared the prices of the cheapest .308" bullets to premium .257" bullets inferred that premium bullets are required for hunting deer with .257" bullets.
I have chased several deer around the hill with the 25 caliber bullets. I rarely have to chase one with30 caliber bullets.
If you can't get clean kills on deer with .257" bullets,you are either using poorly selected bullets,or your shot placement needs work.
If you can not understand how a larger diameter and heavier bullet would put a deer down faster, then it would be impossible for me to explain it to you.
The unfired diameter of the bullet is only a factor when non expanding bullets are used.When using expanding bullets,the expanded diameter is much more of a factor,and if you use the proper bullets at the higher velocity produced by the 25-06,or the 257wby,the expanded diameter of the .257" bullets,is often just as large as that of the slower moving .308" bullets out of a 30-06.The weight of the bullet really means nothing on deer sized animals,in fact some of the heavier .308" bullets don't even expand properly on deer.
I have said this before and I will say it again. The quarter bore is too small for the big stuff, and toobig for the small stuff.
The quarter bore is certainly on the light side for elk and moose,but it is a great choice for deer sized game.If anything,the 30-06 is overkill for deer sized game.