The Maneuver Battle Lab ran an assessment of the Multimodal Hostile Fire Detection (HFD), also a BBN initiative, this past August. The HFD adds an IR sensor to triangulate the crack of the shockwave, bang of the shot, and flash from the muzzle. The system worked well against short range, unsuppressed weapons, but not so well against longer range, suppressed. Promising technology, but still needs some work to provide an instant, precise point of origin of the shooter, just my opinion.
Gathering that data is a perfect job for a few semi-autonomous drones that can fly over area where the shooters might be and therefore be able to gather shockwave and muzzle blast signatures from multiple locations where reflections are less likely to muddy the data.
And then they can designate the target area from above. Or just send in a smaller kill drone.