Yes, a sling is commonly used in various competitions as well, Scott. NRA Highpower is shot with the AR15 and sling. No tripods or bipods or other support. Support "training wheels" as you say are not allowed.
You and I are AGREEING. Crooks was a shit shot. And yes, I also agree... 95% of most shooters, both recreational and military, can make this shot just fine. We are saying the same thing. btw, I do not shoot NRA Highpower. So I'm not trying to defend that specific discipline or anything. I think we are talking past each other because I don't really know what you're trying to argue.
Furthermore, bipods are pretty common in the military. So you might want to rethink the training wheels comment. Did you see the Counter Sniper teams at the rally? They were using carbon fiber tripods from Really Right Stuff. I guess using a Kestrel or Vectronix is "training wheels" too? And yet, 100% of actual mil. designated marksmen were using those at one point...
Again... my previous point was that Crooks was shooting from the prone, without "support" (bipod, bag, tripod, shooting rest, backpack... whatever), using either irons or RDS. And this was all in response to a video someone posted where they said Crooks' shot placement was somehow indicative that there was a second shooter or something to that effect. I was simply refuting that.