Rifles may "like" or shoot some weights or brands of bullets better than others.

I shoot and hunt with a variety of rifles, and I only shoot handloads. I have had good results with bullets from Barnes, Nosler, Sierra, and Hornady. Some bullet manufacturers will show a small icon (coyote, deer, elk, target) on their loaded cartridge box for the recommended use of that bullet. You want to match your bullets to the game that you are hunting...you don't want to hunt elk with varmint bullets.

In .30 caliber, I generally liked 150 grain bullets for deer and 180 grain bullets for elk. A bullet recommended for elk will easily kill a deer, however a smaller, lighter bullet recommended for deer may not cleanly kill an elk.

Bullet placement is more important than bullet diameter, weight, or type. Shooting proficiency increases with range time. Shooting off a bench will show you how accurate your bullets and rifle are. Shooting from field positions will show you how accurate you are.