Niel Jones, and Hart have measuring tools available. They mount on your standard Dial Caliper. The important part is that it has a reticle that has different sized circles inscribed on it for various calibers. You look on the sighter target for a single hole and match the circle that fits that hole. Now you have the bullet hole size. Check on the record for what is supposed to be the widest part of the group. Close the caliper and place the reticle over the farthest portion of the group so it looks like the reticle is placed where that bullet went through the paper. Then you push down on the "dead" end of the caliper, and two prongs stick into the table top and lock that end of the caliper. As you open the caliper, follow the reticle until it lines up with the other side of the group. The measurement should be the group size.... You may have to look at a few places on the same group and choose the widest measurement. It comes with practice.
A little bit of practice is needed to get good accurate measurements. For this reason it is required at matches that all targets are measured by the same scorer, that way everyone gets an equal measure, the idea is if a scorer is off on his measurement, he may be off the same for everyone.
Also, when you are measureing, don't look at the dial, look at the group. Get a good measurement then see what it scores. Don't make a habit of looking at the target number it doesn't matter whos target it is, get a good measurement and write it down. All competitors deserve the same fair measurement. If the holes look small look to the registration to see caliber listed, maybe you are using the wrong reticle. (for this reason a few shooters have shot .22 cal, if the scorer makes a mistake you get a better measurement. It sounds chicken to me but I heard it with my own ears from a Hall of Famer that shoots .22 cal.) For this reason I believe there should be a mark on all targets as a person registers that indicates registered caliber size, (color code maybe) so an official scorer knows what caliber without going to the registration sheet. When you are measuring targets at a match it is important to not have distractions around you, send non officials out of the room.
There is a little "room for error" if you measure a group, and score the target and the competitor has that target remeasured, the new measurement is made if it is within .009 either way of the original measurement, the original stands. The range keeps the contest charge of $5.00. If the original was wrong by more than .009, the fee is refunded and the new measurement stands... could be larger could be smaller. Some matches that are non registered have increased that "margin of error" and they mention that in the small print on the registration sheet. I guess it cuts down on the amount of remeasures when you have over 300 competitors.
Anyway those are the basics that need mentioning... It takes practice before you get solid accurate readings of group size.
Paul
