In case anyone missed it, in this interview producer Larry Liberty talked a bit about how accuracy and damage are calculated in Fallout : New Vegas.
Since our friends at No Mutants Allowed have been so kind and have already done a transcript of that answer, I'll post it here:
What we've completely overhauled - real-time combat. The way you actually calculate damage, the way you aim, the way input works on the controller. We found - in Fallout 3 - that there were actually times where you could miss inputs and overall it could feel unresponsive. So we've tried to make it still an RPG, but through weapon tiering to make it feel appropriate. So if you get a tier 1 gun at the beginning of the game it's not going to feel nerfed and weird and you're not going to aim at something and have bullets fly all over the place if it's a rifle. If you were to somehow magically get a tier 5 weapon at the beginning of the game, you would actually feel a little bit of that weird RPG feel, where "Hmmm, I'm not high-level, I'm missing and it feels weird." We wanted to get rid of that and overall make it feel more responsive and a more compelling first-person shooter.