Comments solicited

[joeb33050]

7.3 SIGHT ALIGNMENT

With telescopic sights, sight alignment is the relationship between the crosshairs, (reticle), and a full field of view. The shooter must place his head so that a full field of view fills the tube, with no dark shadows or crescents to cause no inaccurate shots. He should center the reticle in a full field of view, ensuring that the vertical cross hair is straight up and down so the rifle is not canted.
With iron sights sight alignment is the relationship between the front and rear sights. Center the top edge of the front sight blade horizontally and vertically within the rear sight aperture.

























(Thanks to Bill Pierpoint on the CB-BOOK forum for pointing out this section in FM 23-10 “SNIPER TRAINING”.)

[KYCaster]

This is the first time I've seen that illustration...it might explain some of the verticle stringing I get.

Thanks for posting it Joe.

Jerry

[rbuck351]

What you say is true with a fixed parrallax scope at ranges the scopes parrallax is not set for. Parrallax is the apparent movement of a fixed object relative to another fixed object as you move your eye. Example; If you line up an object on a hill with the top of a tree and move your head left or right the object appears to move. Scopes work the same way except they have a predetermined point at some distance from the scope where there is no parrallax and moving your eye will not produce an apparent move of the target. This point on hunting scopes is usually set at 150 to 200 yds, With parrallax adjustable scopes, the parrallax free point can be set by a dial or an adjustable objective lens to most any distance you choose so that moving your eye around will not affect the point of impact. Take your scope and set it on some thing solid where you can point it at things at different distances. Then without moving the scope, look through it and move your eye around and you will see the parrallax. At some distance you will see the parrallax go away and that will be your parrallax free distance your scope is adjusted for. It will also show you just how much parrallax you have at different distances. The AO on a scope description means adjustable objective which is for removing parrallax at any give distance. Some scopes have a third turret or dial for this.

[felix]

Also, for scopes in particular, the mechanical center must overlay exactly the optical center for the LIGHT PATH within the scope to be centered up front. Making the optical center overlay the mechanical center can only be done at the factory, and that is what you pay for in a high-dollar scope. In other words, the cheaper the scope, the more you have to have an AO adjustment. Never assume the centers are centered on the scope out of the box. The best you can do is to check it by eyeball, by eye movement with the scope out of focus and a half way dark background. The cross hair should not move. If it does, move the cross hairs until it does not. Now, keep it thataway when putting it onto the gun. Sight the gun in by moving the mounts if at all possible and not the cross hairs. In other words, keep the cross hairs centered, mechanically and optically for the basis sighting arrangement. Move the cross hairs only for different ammo. Move the AO for different ranges. ... felix

[Cap'n Morgan]

The shooter must place his head so that a full field of view fills the tube, with no dark shadows or crescents to cause no inaccurate shots.

I don't mind a bit less than full view when looking through a scope. The shadow round the edge will actually aid in centering the scope... and the extra eye-relief comes in handy when shooting full house loads in my 8 lbs H&H.

[felix]

No problem when everything in centered, including the shadows. ... felix

[rbuck351]

Thanks Felix
Good advice. I had not thought of that but reticle and light cross over point being at the same place would be crucial to no parrallax. Centering the reticle to the light cross over and then adjusting point of impact by moving scope would certainly work better. Sometimes I need a little kick so I can see things from a different angle. Buck

[bobk]

Cap'n Morgan,
Thanks for that tip! Makes a lot of sense.

Bob K