Scope, red dot, etc initial sight in

How does one resolve the difference between the center of the bore and the center of the optics when you are trying to align them so you can at least get on paper with the first round.?
My gunsmith had to look through the bore and then move the cross hairs to where he felt comfortable. My AR has a handle so there is quite a difference between centers.

Does anybody make a collimator (Sp) to make this job easier? I have not fired my rifle with the new scope yet but I probably will start at 15 yards as I have no idea where the bullet will
strike.

I use the same method as your gunsmith when I install new optics on an AR platform, set the upper in a rest, see where the bore is pointing and adjust the red dot(or cross hairs)so they are as close as you can get them and then dial it by shooting. If the AR is a flattop and you are using a red dot optic, it is easier because if the irons are on you can adjust the dot so it looks like it is sitting on top of the front sight post and bingo, you are co-wittnesed.

I set my upper on bags at the range and point it at a 50m target. Line the bore, target and dot (or crosshairs) up and go from there. Easy peasy.

Where exactly your rifle/optic combo shoots at various distances is something you'll have to find out.

Mine has a carry handle so U see the problem. I see you used the term co witnessed. Was not sure 100% what that meant. Do now.

That cowitnessed term applys only to flap tops correct? Thanks!

Quote:

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Originally Posted by A. F Medic

That cowitnessed term applys only to flap tops correct? Thanks!

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Yes, that's correct.