what broad heads to use

And I would say Stay away from 2 blades when shooting 40 pounds!!
They don't fly as well as a 3-blade does. Same prob with 4-blades.

I have shot 40 pounds for many years and different b/h's (Muzzys & Montecs, which both I like) but by far the best b/h I've used is the one I'm using now - Grim Reapers (@ 50 pounds). They fly like field points and cut a huge hole! Got three deer down already this fall and I've only just started!