So, as numerous people have posted about numerous times, P/P (and to a lesser extent P/D) just plain does not work right and is a totally borked set. Lots of explanations, suggestions, and workarounds (as well as some defenses) have been given, some are good, some aren’t, but most dance around the most critical issue affecting the set by far: Vital Shot. Vital Shot has a sluggish rate of fire for its stats, making it offensively weaker than it should be in general, but there’s more to it than even that:
You see, the way Initiative works makes it imperative that your autoattack, which is your only free source of DPS, deals appreciable enough damage that you have the freedom to be flexible with the way you use your Initiative. This is actually a problem with both SB and MH Pistol, but is masked a bit more with SB due to how well it performs in specialized roles, largely due to Cluster Bomb.
P/P’s major problem is that Unload is both significantly stronger than Vital Shot (while still not being amazing) and benefits from different stats. This pigeonholes the player into building power/crit for maximum efficiency, which widens the gap between the two even more. This in turn forces you to play P/P in such a way that you’re constantly dumping all your Initiative into Unload in a frantic attempt to prevent reliance on Vital Shot from instantly cratering your DPS. This also means you are left with no resources to use elsewhere, meaning you are perpetually crippled with regard to mobility and utility at a max range of 900 yards. In short, the inequality of the two completely destroys the usability of the set.
What needs to be done? Regardless if it’s a bug or not, Vital Shot needs to have a faster rate of fire (maybe something much closer to its stated Activation speed like the Rifle) or do significantly better direct damage so it can provide decent DPS support for both P/P and P/D.