Question about benchrest shooting

[zahc]

I have no experience with benchrest competition. But sometimes I hear about group sizes of less than the bullet diameter. Sometimes far less. Recently I was reading about a rifle that could print 0.030" groups. My question is, how do you actually measure group sizes that small?

[HankB]

I would think that it's done by determining how much larger the hole in the paper is than the bullet diameter.

[brimic]

To complicate things- I think they use a different target insert for each shot so that you can't cheat and simply put a few shots into the dirt.

[zxcvbob]

Or a moving paper backer?  Like a scroll.

[griz]

Yep, they essentially use outside edge to outside edge and subtract bullet diameter.  They have fairly fancy ways of deciding where the edge is since any bullet tears the edge.  And it is only group size that matters, not where the group is in relation to the center.  That way you don't have to shoot the aiming point away.

[MechAg94]

I imagine you need to make sure to use the right paper so the holes are sharply defined.

[charby]

To complicate things- I think they use a different target insert for each shot so that you can't cheat and simply put a few shots into the dirt.

What little I have done (Varmint benchrest), one target one shot. The paper target has 10 separate targets of various sizes on it at 200 yards.

[French G.]

Track down Bogie on facebook if you want to get into it, he knows a fair amount.

[230RN]

I imagine you need to make sure to use the right paper so the holes are sharply defined.

Lore:

Real target paper is produced so that the individual fibers are randomly oriented.  This, so the holes will be nice and clean.  Also, I believe the fibers are very short for the same reason.

I'm sure you've discovered how fragile targets are when handled, for this reason.  You can hardly roll up a B-27 or similar sized target without ripping it.

Using ordinary paper for targets results in elongated holes since the majority of the fibers are more or less lined up in one direction.

Ordinary paper tears straighter in one direction than 90° away because of this fiber alignment.

Wadcutter bullets are used to make handgun target scoring easier since the holes they leave are very clean, making it easier to determine if they touch a scoring ring.

There are many types of scoring magnifiers.  Sample:

       

Some old time pistol target shooters preferred .45s over .38s because the bigger hole diameter made it more likely to touch a higher scoring ring. After all, firing a 16" cannon shell at a 25 yard bullseye target would automatically result in a 10-X bullseye no matter where on the target the centerline of the shell struck, right?  :)

Terry