Haha, I correct your mis-reading and I did the same thing. I glossed over the fact of the 15 shots at each range part. Glad you can add because I couldn't.
And yes, Tubb is an amazing shot.
I'm curious now... When they said open sight, I interpreted that to mean "irons". So, what do they mean by single lens then? Are they meaning a red dot sight like a primary arms or EOTech?
High power rules allow single lens AKA magnifier (usually in the front sight, unless shooting "service" then the lens goes in the back sight) that has about 1.2-1.5x magnification and removes depth perception (the target appears in the same plane as the front sight).
Holographic and red dot sights are awful for long range shooting - so legality is moot. (works wonders in bullseye game though).