Want to work up to 1000yd...need build advice on the reasonable for the rifle

[Sticks]

I'd thought LR55 would have said that brass makes an accuracy difference when you are looking for that last .1 MOA to a perfect single hole group.

Barrel, bullet, powder, primer, action, optics, mounts, chassis, trigger, and last but most importantly....the person pulling the trigger is where the accuracy is at in a rifle.