I'm planning this speed run with a friend, our situation now is that we've just killed the Wall of Flesh, are geared with Molten gear (Armor, Imp, Bow, Sword, etc.). We're at 300 HP, but we'll probably make sure we are at 400. Our plan is to kill the destroyer once, to get at least 20 Souls of Might, to craft the Megashark.

We've tried various weapons (Molotov, Grenade, Minishark, Molden Fury), but the problem is that the DPS is just not enough. Next step is that we'll try to go pick up a Handgun from the dungeon to get a Phoenix Blaster + Explosive shot.

So I'm wondering if you have a suggestion for us on what weapon to use for this, keep in mind that speed is of the essense, part of our challenge is in fact not taking 1-2 hours to craft 2 Titanium / Adamantium armors and such.

Edit:

We've tested a new technique yesterday with considerable success!

We used stacks of Grenades, along with a very very long skybridge about 100/150 above surface. In the middle of the skybridge, we've setup 3 levels high (about 50 in between). Camp fires spread accross.

Gear-wise, we have Molten gear, each a Obsidian shield, Harpy / Demon wings and a magic mirror. The strategy is to drop grenades at the worm, when our HP get's too low we rurn away from the spawn then teleport. Our spawn is setup next to the nurse. Heal up with her and return to fight.

This takes about 5-6 minutes, after which we gain access to Megashark + Explosive shot which unlocks the rest of the speed run.