centering the reticle on a scope

[crow001]

can anyone out there please help this confused aussie with this problem? I have purchased a Bushnell 4-12x40mm scope, with parallax adjusting ring and before mounting it to my rifle I am following the instructions that came with it concerning the centering of the reticle. My problem is this.... after setting the scope up in a "v" block and focusing on a target at 25 yards as per the directions, spinning the scope and adjusting it untill the reticle stays perfectly central I then tested the scope on a target at 50 yards and the recticle is out of alignment by a good 2 inches! I adjusted the parallax ring to suit the two different distances on both occasions.Can anyone help?
cheers "crow001"

 

[tazzman]

Hello crow001,

First off, welcome to the forum!

Now for your question: You centered the reticle using the V-block.
When you say that you tested the scope at 50 m, do you mean that you mounted the scope on a rifle and shot @ 50 m.? or that you performed the V-block test again @ 50 m?
If you performed the former, then the 2" difference can probably be attributed to the fact that the scope sight line is parallel to the barrel bore line, not set up to intersect the bore line as it should be.
The V-block instructions are there mainly to set up adjustable scope mounts so that the scope is roughly centered to bore line and provides the shooter with the most left-to-right adjustment capacity(for rear mounts that are adjustable) and for up-down adjustment capacity(for Burris signature rings)
I do my parallax adjustment by bobbing my head slightly side-to-side and up-and-down to observe reticle movement using the target as reference, then adjust to reduce perceived reticle movement until I can't notice it.
Focus, on the other hand, is done against a bright background and is adjusted to obtain the sharpest reticle outline possible. If done with eyesight 20/20 (I don't so I do this with my eyeglasses) it should be done once for that scope installation.

Keep us informed of your progress. I hope this was a litlle bit helpful.

Phil aka tazzman

 

[alf]

The fastest way to center a reticle is to butt the objective lens up against a mirror. When you look in the eyepiece, you'll see two lines, adjust the turrets till they coincide, and you'll be there.

 

[kelbro]

The fastest way to center a reticle is to butt the objective lens up against a mirror. When you look in the eyepiece, you'll see two lines, adjust the turrets till they coincide, and you'll be there.

Exactly.

 

[Nomad47]

Wow. Great responses by everyone. The only thing I can add is actually just to say the same thing, just a little differently.
The V block is to have the scope reticle mechanically zero for maximum adjustment as already stated. Rings, bases, and tapped holes are NOT perfect, so some adjustment will be necessary right out of the chute once the scope is mounted. Also, if the scope POA is parallel to the bore, POI will be as low as the scope is as high above the bore at the muzzle AND it will never get any closer. In fact, POA and POI will get further and further apart as the distance increases.