Smith910,
The X ring (center ring) on the USBR target is .100" in diameter. If your shot touches that ring, it's 10 points. If your shot obliterates that ring, it's a 10X. The number of X's are used as a tie breaker.
Here's a gif image on how to score a benchrest target. Shooting this target is a challenge, whether you're competing or not.
http://home.kc.rr.com/pichouse/rfc/1.gif
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Freedom has a flavor the protected can never taste...
USMC 8652, 2531, RVN Jun '66, - May 68
Some of my rifles