The last time I shot for record at the 600 yard line, with handloads, I shot 200-15X. That translates to 15 out of 20 into a six inch X ring, and the other 5 in the 10 ring. I didn't get to see the target afterwards, as they had pasted a new face on it by the time I got down to the pits.
The rifle itself is right off the shelf, and out of the box stock. I really need to get it to a smith and have the action trued, and the barrel replaced with something better.