My 19th level character just back from an expedition to Vault 34 and sold off 15K worth of loot. He has NOT been through Old World Blues yet. Now that he's flush, what would be the best GRA/OWB weapon to get? I've noticed the Nuka Breaker in Ralph and Mitch's inventory, which seems to have a very high damage and supposedly has electrical crits. Problem is, my character has the Heavy Hitter perk, which reduces the amount of crits. Would it be better to get the Breaker, or try to pick up a Protonic Inversal Axe? Explosives are another option, but this character's skill is only at 75 nor has he taken any explosives perks. I'm intrigued by the 25mm APW, but I don't really know what it does aside from fire small grenades.

Side note: Had a blast carving my way through Vault 34 with a Fire Axe. Only other weapon I had to use was one pulse grenade.

Heavy hitter doesn't reduce critical chance, just damage. It's awesome for Two-Step Goodbye & any character with a low luck who wants to go hand to hand.

I haven't used the Nuka Breaker, but the Protonic Inversal Axe is awesome against almost every enemy even for my character who doesn't have a Melee focus. Have you considered the X-2 Antenna? It's a VERY respectable weapon in the hands of a melee combatant. If you're worried about Heavy Handed, Old World Blues gives you the option to respec your traits.

The 25mm APW is a lightweight grenade launcher capable of rapid firing grenades normally reserved for the Grenade Machingun. Given that GRA introduces Plasma, Pulse, & Timed variants of said grenades, the APW can counter basically anything. 75 points in explosives is just high enough to use effectively, although taking Demolitions Expert at some point can only help you.

-Nukeknockout

The 25APW is basically the Grenade MG for Couriers on a tight budget and/or who watch their carry weight. It's also somewhat safer in close quarters because 25mm grenades have a smaller blast radius; however, incendiary 40mm grenades have even smaller AOE while retaining higher DAM.

I would advise against relying too heavily on Missile Launchers in OWB, though. Spawning distances can be somewhat short, and the terrain rarely gives you the distance for a missile shot. However, on occasion you can nail a tight crowd of Y-17 Trauma Harnesses and Lobotomites with a single well-placed missile.

On the other hand, there's a perfect condition Missile Launcher on a rock just S of the Y-17 Medical Facility, so I don't really know xP

-Nukeknockout

And a group of targets usually spawns nearby, yes. But go a short way north from there, and you're hunting nimble nightstalkers in a maze of tubes that is not at all a missile-friendly environment.