Another thing that I've noticed is that you wont always be aware when a pirate base has been "defeated". I took out a base, killed the core, removed all the turrets, then spent another hour or so blasting at it before i realized that it was in fact already dead, and had been for some time. It took me warping away and then back for it to be listed as "derelict". So, keep a small salvage beam handy and try to salvage a block if you think you killed it. If its dead, you get salvage. If not, you get a big warning telling you to keep searching for that faction block!