While I love the idea of a drilling, any hope for an accurate .223 insert for long range small targets is pushing envelope beyond usefullness in my opinion. What sort of precision is to be expected is the real question. I hope to hear opinions but would really like to see performance first hand. The 223 would need its own sighting system (on and off) too.
My guess is that a 5 shot group shot at 200 yards would be bigger than a fox but I've been wrong before.
Serious fun on a prairie dog town requires a 1.5" grouping at 300 yards. This is opinion, not fact.