Borderlands – Do Sirens get any bonus out of Explosive weapons

I was hoping for a more authoritative answer, but after >50 hours of gameplay using mostly elemental weapons, I'm pretty darn sure there's no longer a tech pool.

Elemental guns deal consistent damage and elemental effects are randomly distributed. The visual effects are consistent (either a shot was elemental or not, you can tell by watching the bullet impacts).

This means that slow firing weapons are worse for stacking elemental status effect damage than high rate of fire weapons, which is sort of the opposite of how the old Tech Pool worked. The status effect chance % as listed appears to be the only relevant factor for "procing" a shot, though it's affected by skills, class mods and Badass bonus stats.

The health bar has to be yellow for corrosive to be extra effective. It still works normally on most normal health bars. Fire is best against most normal health bars (except the ones of fire creatures as they will resist). Shock is great against shields, especially useful in the second playthrough when much more things have shields.

In general you should be able to judge what is effective, what is resisted and what is doing normal damage just by looking at the damage numbers floating around enemies.