Scope Alignment Question

[CSiebert]

I have been shooting my new rifle behind the house this week and I have noticed that when I go from 150 yards (my closest target) to my other target @ 400 yards I am about 3 inches right this is in dead calm conditions and I have noticed this more earlier in the week when I had zero wind. After I zeroed @ 400 I reshot the 150 target and was 1 inch left. I am shooting an FN Pbr 308.

My Question is if my rail is not perfectly centered on the reciever will it cause the shooter to put windage imput in the scope as you increase yardage? If so are there any ways to fix this problem? Can you loosen the scope rings and try to retighten to see if they settle a little closer to true zero in relation to the barrel.

 

[dpreston]

Re: Scope Alignment Question

i would bet that your reticle is canted. That would put you dead on for your 100 yard zero, and as you dial up to your 400 yard target, your actually holding off a few inches not even knowing it.

 

[81sfo]

Re: Scope Alignment Question

Set up a Target at 100-150 yds,with a construction level draw a vertical line with a thick marker.place several shoot n see circle targets along that line starting at the bottom.zero on the bottom Target and make scope adjustments to hit the circles ,you should see how far off your groups turn out to be left or right of the line.remember only use windage knob to get on zero on bottom Target,all others use elevation knob only.hope I explained this correct.
Doing this should tell you if your scope reticle is canted and you need to loosen rings to readjust accordingly.a canted scope will cause you to be off Target at the longer ranges.

 

[CSiebert]

Re: Scope Alignment Question

Thanks I bet you are correct. I should have known that.

 

[VKC]

Re: Scope Alignment Question

I agree that your scope reticle is likely canted. I had a similar problem with my scope, tried a feeler gauge between the scope and base to level, but still could not get it perfect. When I zero'd at 100 yards, my groups would be 1" to the left at 200 yards...kept thinking is it me, is it the wind, is it the scope? At least for me, it was difficult to tell, and ammo isn't cheap. I finally got an EXD Engineering Vertical Reticle Instrument, and fixed the problem.

http://www.brownells.com/.aspx/pid=6097/Product/EXD_ENGINEERING_VERTICAL_RETICLE_INSTRUMENT

It will likely be more accurate then shooting and dialing up/down your scope, save you ammo costs and time. A slight scope cant is difficult to pick up otherwise, but can make a big difference at longer distances.