I mean, 40mm requires a couple feet to actually arm and explode on impact, but it’s still bad TD.
There's no excuse for the bad trigger discipline, but fortunately for her, depending on the specific type of 40mm explosive round, the minimum arming distance ranges from about 3 meters to about 15 meters. It takes a few rotations for the parts of the fuze rotor to line up. If you're shooting the buckshot rounds, I think some of it would probably bounce back at you though.
I wish I could afford an ACOG with the RMR on top; maybe down the road...