A decent number of cities have gun shot detectors. Be prepared to make quick and clean escape.

Loud, gives you away immediately, you need good aim, difficult to conceal, shot spotters triangulate your position almost instantly in any major city, firearms are registered to owners so either you go black market and hope you don’t get caught or go on a list of registered owners, leaves behind bullet and maybe casing which can be traced to type of gun, lots of laws to throw at you when they do catch you to put you in prison for a long time.

I mean if you could do it like they did with the DC shooter that seemed to really flumix them which I would think they had those mics all over that city. I dont know enough about firearms to tell you if there is a way to make the inside of a trunk more sound proof, but if you really wanna shot them cameras, I would think that would be a good baseline.