Check in with D Rock at Rimfire Central. He makes them.
I should note that I do not have any financial interest in this. I just think it's a great product!
I do not believe it would work on .223 as the bullet is internally lubed, not heeled, and would be pushed into the case. I don't suppose it would hurt to ask him though!
I just took another one that was on my range near the 75 yard marker. No time for 'scope dial-in; I cranked it to 100yds on the objective and fired, using Kentucky windage. I hit it right behind the ribs.
Instant pile-up. It thrashed for less than five seconds. A LRN at this range and placement would have let it run - I've even nailed squirrels with Remington subsonic HP (no expansion) in the chest and they've required follow-up shots.
At this range it was going about 1040fps, maybe a hair less due to the changed BC.
I still don't believe in hydrostatic shock below 2,000 fps or so, but I'm starting to reconsider other types of shock which I've dismissed in the past.