[siggypoo]

I've browsed and searched both ASC and the interwebs in general, but I've yet to find a concise explanation of the benefits an detractions of BBs of whatever weight in whatever gun.
I think I understand that the .3Xs seem to be more for sniper rifles, .20s are a sort of chrono standard, and .12s are strictly for low-end stuffinks.
I guess I'm asking what the benefit or detraction might be if I threw .3X out of my We Scar CB as opposed to the .20s I currently use. Sure, they have greater mass, but does their range suffer because of that mass? Is there a weight range that is safe for my GBB? I mean, can a greater weight put too much gas pressure in the wrong areas, weakening or wearing them? If I put .3X in my We HiCapa or We Little Bird, would that be of any use at all, or should I stick to .20?
Whichever the answers...WHY?
An explanation of why whichever reasoning is most important.
Thanks for any advice you can give.