Would have been better to continue with your original thread and just link to this four-year old thread if needed. Re-asking your question here could be considered a cross-post, which is frowned upon...
But, back to your interesting problem: you might get a better response if you post a figure showing one or more clear samples of the waveform that is produced when a bullet passes by a microphone and when the sound of the shot reaches the microphone (as DrDiettrich mentions in post #18 of your original thread). Exactly what does this "rising waveform" that you are trying to detect look like (in terms of voltage vs time)?
PS: and, out of curiosity, what microphones are you using?