I gave the guns different startup and endlag as a balancing mechanic. If the MP7 shot at frame 2 like the pistol, then there'd be no reason to not use it. If I continue the project, I'll make the guns reference your direction at the time of the button press instead of the direction at the time of shooting.
The most broken build RN is 3 snipers tied together. The endlag of the first 2 get interrupted by the next one. Try speedrunning and see what time you can get. My record is 2 minutes flat. Here's a tip: increase your speed like crazy by chaining dashes and slides together