As for 10 sectors range, that must be with some serious weird mod.
Design range, not strike range, and as I've never modded the game I sincerely doubt that there's any issue with mods affecting things. Recovered derelicts tend to have this kind of range (and I usually see several of those in pirate hands on a prewarp start), whereas the pirate start-of-game designs tend to have shorter ranges (~3-4 sectors design range or so based on a quick check of player-pirate autogenerated start of game designs, at least for escorts/frigates/destroyers). Effective single-target strike range is a little under half the design range; a recovered derelict with a design range of ~10 sectors can reasonably strike targets within ~5 sectors of its nearest refueling point if the strike originates from the refueling point, and can probably conduct raids on several targets which are reasonably close to one another as long as those targets are within ~4 sectors of the nearest refueling point.
I agree that pirates aren't terribly likely to strike targets more than ~2 sectors away, at least if they're using their start-of-game designs or ships which aren't much more advanced than that, but it can and does happen if they get their hands on a derelict with a lot of range or don't have any closer targets that they can hit, or if another pirate faction surrenders to them and they suddenly get a bunch of ships which are relatively distant from their own bases (especially when the raids can be conducted in such a way that the ships are always getting closer to a refueling point).
< Message edited by Aeson -- 10/7/2015 8:30:52 PM >