What ammo...
Bow Cephus--Regolith nailed it:
Best bet for you would be to try a bunch of different loads for your rifle and find one that is accurate out of your gun.
Each rifle is an individual, and most have "likes" and "dislikes" when it comes to ammo.
That said, IMHO, the 165 grain bullet is the ideal for a .30 cal rifle--You might well begin yr quest there.
Yeah, buy the common, cheap Rem and Win and Fed ammo and try it--If it produces acceptable accuracy from yr weapon there is no need to look further. You don't need Uberbullets for deer; the ordinary ones will work just fine.
Take rifle and ammo to be tested to the range. Benchrest the rifle so that you're testing the rifle/ammo combination, not your aiming/shooting ability, shoot targets with each brand of ammo, and probably one of the brands will work notably better. That is what you should use with THAT rifle.
Good luck in yr quest. Enjoy. And, as always, the journey is part of the destination.