Generic questions regarding scope (initial sight in, 20MOA rail, vertical range)

[rarick123]

I just picked up my new NF 2014 Competition yesterday, and my Seekins rings and 20MOA base will be here tomorrow, but thinking about the install got my head wondering about a couple of things...

First, according to the NF website, this scope should have 55 MOA of vertical adjustment. If I start with the turret bottomed out, I count 565 clicks (1/8 MOA) until I feel some resistance. I could go farther, I'm sure, but why risk it... anyway, it's the fast elevation knobs, so one complete revolution is 10 MOA, and sure enough, 80 clicks gives me one complete revolution. Now, I ain't no rocket surgeon, but even by Pentium math, 565/8 = 70.625, or 70 and 5/8ths MOA, no?

I counted so that I could find the mechanical center on the elevation, but that too got me wondering... If I'm mounting this to a 20 MOA base, wouldn't I start it at the mechanical center, then go down 20 MOA to have it (roughly) back at the pseudo-optical center?

Again, assuming my math doesn't totally suck... let's call it 70 MOA of elevation that's available on the scope. Center would be at 35 MOA, so I'd have 35 up and 35 down to play with. If I drop that down by 20 because of the base, I would start at 15 up from the absolute bottom, so I'd have 15 down and 55 up for the total available adjustment?

 

[aj300mag]

You're assuming that the reticle would be mechanically centered with a 0° rail. That may or may not be true.

 

[Old Navy]

You're assuming that the reticle would be mechanically centered with a 0° rail. That may or may not be true.

+1 No way of knowing what you are going to have. Later! Frank

 

[aj300mag]

Should I give him the bad news and tell him the scope was shipped from the factory at optical center?

And I never verify range of travel without looking through the scope to insure that the reticle cell is moving with each click.

 

[Keith Glasscock]

To put it back at the approximate optical center, put the objective end against a mirror. Adjust the scope until the two sets of crosshairs coincide.

I usually have to do this at minimum power.

I agree that checking knob movement is best done while making sure the reticle is moving. When going up, the elevation screw could move away from the tube inside the scope giving one the false sense that the scope has more travel than it really does.

 

[aj300mag]

To put it back at the approximate optical center, put the objective end against a mirror. Adjust the scope until the two sets of crosshairs coincide.

I usually have to do this at minimum power.

Yup! The trick is to keep your eye away from the lense far enough to allow light to enter through the eye piece.