Re Brrt....
"Brrt" was a result of the need to Kill an armored vehicle with one burst, without a ranging sensor. Hence a lot of rounds were sent downrange into a tight pattern (function of rate) that hopefully centered on the target. But add to this a lot of bursts/mission (there was a lot of armor expected through the Fulda Gap) and consider that every shot required all 1350 rounds in the system to move, and the whole shooting match (so to speak) started to get heavy.
I suspect today that you'd use l@ser, radar (possibly lidar), and possibly guided rounds to increase P-Hit, and go for a shorter burst and more modest rate.