Bore Sighting Question

[Guyon]

Can someone explain to me (in layman's terms) why, when you're boresighting a rifle, up means down and down means up while right means left and left means right?

Was boresighting a new VX-II Leupold today and noticed this for the first time (was I asleep when I boresighted the other three scopes I've mounted??? ). Today, a little trial and error quickly showed that moving the verticle adjustment up actually moved the reticle down (in the sight picture) and moving the windage adjustment right actually moved the reticle left.

Found this article, but I still don't quite get the *why* part. Is there another way to think about it?

http://tactrain.net/scopes.htm

Couple of excerpts:

"As you make adjustment for windage and elevation correction from a group that you shoot on paper, everything works normally. But when you sight down your bore (that should actually read "through your bore") and then turn the adjustments, that's when things get a little fuzzy."

and

"So…..when bore sighting, Up is Down and Down is Up, just like Left is Right and Right is Left! I know, why do things have to be so damm complicated. But look, here is the Redneck method…..move the cross-hairs in any direction….it doesn't make any difference which direction, just move it. Now, if it moved the wrong way, adjust it back the other way! The only difference with the Redneck method, Murphy gives you a guarantee you'll go the wrong way first almost every time!!!!"

 

[redneck2]

Suppose your first shot is 3 inches to the right of the bullseye and 2 inches high...that means you want to move the bullet left 3 and down 2 (inches). At least that's the way we think of it

thing is, you don't move the bullet to the bullseye, you move the bullseye (actually the aiming point, the crosshairs) to where the bullet is hitting. Hence, the "directions" on the knobs are backwards

To make life easier, set your target at 25 yards. Shoot from a VERY solid bench (I use a Black & Decker workmate). After your first shot, remove the covers from the knobs and clamp the rifle in the workmate with the crosshairs exactly on the aiming point. Now, without moving the rifle, adjust the knobs until the crosshair is exactly on the bullet hole. You'll usually be sighted for about 125-150 yards depending on the height of the scope above the bore.

 

[DMK]

A fixed rifle will always put the bullets in about the same spot. You either move the crosshairs to that spot or move the rifle to put the bullets in a different spot.

1) When sighting a scope, you first have to shoot the rifle to make it put the bullet where it wants to. Then you "steer" the crosshairs so that they point to the same spot as the rifle keeps putting the bullets. So the rifle is pointed at the bullet holes and you are making the scope "conform" to the same spot as the barrel of the rifle is throwing the bullets. The rifle stays still and the crosshairs move.

2) When you are shooting, you are focusing on the crosshairs. To adjust, you appear to be steering the bullet holes to the crosshairs. In affect, you are moving the barrel of the rifle towards where the scope's crosshairs are pointing. (the opposite of above) The crosshairs stay still and the rifle moves.

Now, method #1 has to be used to sight in a scope because you want the rifle to be fixed solidly where it can't move so it will keep putting the bullets in the same spot. You can't use method #2 and steer the rifle towards the scope if it can't move so you have to steer the crosshairs to the rifle.

 

[Yooper]

According to the linked article, adjusting the windage and elevation knobs adjusts the image with respect to a constant crosshair using the lenses within the scope. We think in terms of moving the crosshairs. If we want the crosshairs moved left, we adjust for left, which moves the image to the right, and we perceive this as a left movement of the crosshairs.

 

[Guyon]

Makes sense now. You're basically moving the image, not the crosshairs.

So when you seem to be moving the crosshairs down and left, you're actually moving the point of impact (or the image in your sight picture) up and right. These latter two designations (up and right) will correspond with the designations/arrows on the scope adjustments.

Thanks guys. Saying it a different way helps out sometimes.

Glad those fellers at Leupold didn't have it backwards.