Optics

[G.S.]

if you can understand & agree that the eye should be aligned with the optical axis of the scope to in order to avoid the effects of parallax, then weld check/ head position matters.

[Fox]

if you can understand & agree that the eye should be aligned with the optical axis of the scope to in order to avoid the effects of parallax, then weld check/ head position matters.

One point of a scope is that the cross hairs do not shift, the cross hair moves within the scope when you move your head around but it stays in the same spot, in and out or up and down does not matter, the scope axis is not changing.

Put the gun in a vice aimed on a point and step back and look into the scope, the cross hairs should remain at the same place.

[jaycee]

Importance of " Cheek Weld when Shooting ":
RIFLESLINGER’S RAZOR AND THE IMPORTANCE OF PROPER CHEEKWELD
Why is cheekweld so important? It has to do with parallax. Parallax can be illustrated by trying to read an analog speedometer from the passenger seat of a car. Because the seat position is so far out of alignment from where the speedometer was intended to be read, you’re seeing the speedometer needle over a slightly slower number than it is read from the driver’s seat. If you were able to look at the needle from outside the driver’s window, you’d see the needle over a slightly faster number. The difference in both instances would likely be only 2-3 mph.

With a rifle sighting system, whether it be open sights, aperture sights, or a scope, your head position must be consistent. If it is not, you may see the same perfect sight alignment and you may obtain a perfect sight picture, but you will get erratic results. It will be frustrating because the source of the inaccuracy may not be readily identifiable.

Why did it take me so long to get my cheekweld right? What was my resistance based on? I think that my “reasoning” is probably pretty common. Hunting rifle stocks are not made to fit well. This is, of course, not advertised in the gun rag ads or articles (longer ads). So none of us really have it in our heads that our expensive rifles are going to need a bunch of adjustment right out of the box.

go to google and you will find pages and pages of the why,s of proper cheek weld.