If you're not reloading, you'll have to try a box of as many brands and bullet weights as you can to find the ammo your rifle shoots best anyway. Once you've found the ammo, you need to sight in on a bench, then practice with it, off hand, at 100 yards until you can hit a 9" pie plate every time.
Just sighting in with your hunting ammo isn't good enough. You have to know exactly what the rifle and ammo will do in every weather condition. Cold weather can cause a change of POI with factory ammo. Can with reloads too, but that can be the ammo or the rifle. Both can be modified for weather. A wood stock that isn't sealed in the barrel channel can warp and change the POI.
Reloading lets you shoot more with ammo that is tailored to your rifle. Lets you adjust the load for different ambient weather conditions too.
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