check out precision rifle blog. they have all kinds of articles on what all the "pros" are using. Anything from what bipods, to what calibers, what barrel length, what contour, which chassis, which muzzle brakes, which triggers. all laid out with graphs and percentages.
from my very little experience only gained from research when ordering my first barrel. it seems the most common calibers are all the 6mm and 6.5 variations. 6x47, 6dasher, 6.5x47 (most common with the pros), 6.5c, 6mm, etc.
Medium Palma, Heavy palma, MTU, m24 are the most common contours with 26" being the most common length.
google "barrels, what the pros use" or "bipods, what the pros use" etc. use that format and look for the precision rifle blog links.
i know it's only 1 source but it seems to be pretty dead on with what i see on the forums and at the one match i've been to