guns

Scopes are expensive. Good news is if you make a good buy you probably won't have to buy another for a long long time. Vortex is decent for the price.

Get a good scope mount too. The best scope can't perform if the mount isn't solid.

Bipod, sandbags, hunting tripod, something to keep the rifle nice and steady

After a while you'll want to try different types of ammo to see what the rifle shoots best.

But most importantly and most overlooked, all rifles are trash if YOU are trash at long range marksmanship. Read up. Put your rifle parts together correctly and learn as much as you can on and off the range