Depends on the bullets construction.
"I've not seen data about the jacket design on the regular 125-grain bullets. Dunno if it's a heavy varmint bullet or a light deer bullet. The jacket design matters, to me. If it's a heavy varmint bullet, it's heavier than need be--and might fragment on a deer's bones."
As said above, what a bullet is useful for depends on its construction not on the weight and what you think that weight should be used for.
Just because Speer makes a 130g .308" bullet for varmints does not mean all bullets of that weight or lighter are made for varmints.
The Sierra 125g .308" bullets is for hunting game.
T.