Your method works quite well for 106MM rifles also. just increase the target distance to 3,000 yards or more.
How accurate are recoilless rifles? And what kind of practical range can you get out of them?
A farm equipment dealer in Nevada told me that they used 106’s mounted in jeeps to take out snipers during Tet. He was quite PO’ed about how the press mis-represented Tet as some sort of rout for our guys - he said “We had to hustle, sure, but we were never retreating. Snipers? Pfah - we’d get a radio call, go zipping over to a street that led up to the building with the sniper(s) in it, let fly with a round or two from the 106... no more sniper, no more problem. Then we’d go onto the next radio call...”
He didn’t mention what sort of range they were shooting at — just that the 106 worked like a charm and then some. Said that there were days they were in “high demand.”