A preface This build has 3 parts: a gun focused headshot central component, a "kill everything with your ult" section, and a spirit escalation theme that makes your fly bullets do ludicrous damage late-game. Pretty much every green item except Bullet Lifesteal is optional, but they are useful. The general order is that we focus on the gun, then ult, then gun, then ult, then spirit damage. You should buy green items when they feel appropriate, usually based off your matchups. Hit headshots and be good.
Laning Go by vibes, if you're taking damage Restorative, if not Headshot > High-velocity Mag > Hollow Point. Bullet Lifesteal as soon as you can, sometimes first if you're really agressive. Get Extra Charge from the ult section before 3k.