Cauldron patch changed ghost heat limits for the IS ppcs and desynced ghost heat limit of lgauss and ppcs. Which means you can fire all weapons at the same time without ghost heat for juicy 50 pinpoint alpha strike at 540m. First charge up the gauss and then release the shot with ppcs. However Nightstar suffers from huge convergence issues and i wasn't able to land my shots consistently. I just suffered while playing this build. But I see quite a lot of Nightstars trying it lately. I don't really think it is a good build at least in my hands (I was wondering if it shouldn't be a meme). _
PPCs and Light Gauss also have significant differences in velocity unless the chassis has PPC velocity quirks. That will make landing all your shots a lot harder.
https://mwo.nav-alpha.com/mechlab?b=9000ed97_NSR-9J I would recommend the ER PPCs to better sync velocity and range. I keep thinking about trying this, but the hardpoints are so spread out.