I've never heard of the .224 Valkyrie round but, it seems interesting.
This video was shot at my friends farm and my friend is one of the shooters in the video. I'll ask him more about the round the next time I see him. This is also the range I've shot at many times. This past year he's made a bunch of improvements to the backstops. One of these days, we'll get smart enough to put large tarps on the ground to catch all the brass.
https://www.youtube.com/watch?v=VG9V1jgXUp4