A couple of recommendations for you. I personally wouldn't mess with anything an AEG type (electric). They should be the most precise since you don't have to worry about the fluctuations involved with gas and just less trouble in general to run IMO.
I would also stick with the Marui brand of guns. The better guns start with their electric motors anyways, why not get the whole thing from them. I actually have the Marui version of
this MP% and have bumped it up to shoot around 350fps. I love it.
Some better sights to check into are
www.precisionairsoft.com and
www.extremeairsoft.com.