How much adjustment to zero

[kwyeewyk]

Trying to mount a new scope on an old rifle (73), the old ring/base combos had a shim under the right side of the rear base. When I first mounted the new scope tried without the shim since it seems more level and aligned that way. Once the scope was on, it appeared to be offset to the left. Took it to a gunsmith and he put a bore aligner on it and adjusted the windage and thought it would be alright. When I tried to sight it in at 100 yards I used the rest of the windage adjustment and still couldn't get zeroed. Of course the gunsmith is out of town for 2 weeks. So I loosened the mounts for the rings and moved the scope to where it appears to be perfectly aligned--at that point it takes close to 20 MOA of adjustment to get it bore sighted (total windage adjustment is 65, so using over half of that side"s adjustment). When I move the scope to where it's bore sighted and zeroed for the scope's windage and elevation, then it is obviously offset to the right of the barrel.

I think the front base is slightly offset, but considering that, it's still odd to me how much adjustment is needed when the scope appears to be aligned, and how far off alignment the scope appears to be when bore sighted to the scope's zero point. This makes me wonder if the scope's zero point is offset and I should consult manufacturer? Or do I just set it where it's most aligned and use the 20 MOA of adjustment to get it zeroed, which would still leave 15 MOA of windage adjustment which would be more than plenty for hunting at reasonable ranges and wind conditions? How much windage adjustment to get a rifle sighted in is considered "normal"? Long term I'll look into trying to get the front holes re-tapped, but wanted to understand what was happening and if I can get it shooting okay for now.

Thanks

 

[kwyeewyk]

Alright, I re-mounted the scope and it looked okay for alignment, bore sighted at 100 yards and it looked okay, took a few shots at 100 yards and am circling the bulls eye with about 5 MOA elevation and 8 MOA windage. WTF? I guess it just needed to be re-set on the bases, wouldn't have thought it could be that far off from that, the gunsmith made sure it was seated well since he figured that was the problem to start with. I guess now I just test it out and if it holds zero and maintains at variable yardage I'm good. Makes no sense to me but if it works I'll take it! Windy today so I'll try to get a solid zero on a calm day.

 

[ImBillT]

If your action was under $1000, and your rings and bases can be purchased in a chain store, there’s a reasonable chance that you’ll have to do a fair bit of dialing to get zeroed. If your action was manufactured without the use of CNC equipment, that probability goes up further. Windage adjustable bases like any of the Redfield copies(Leupold STD) will help a lot here. Burris Signature series rings also have inserts that can be used to roughly adjust your zero before you start dialing your scope. It’s always nice to have your scope near it’s mechanical center for a no wind zero, and the distance at which you want to be mechanically centered depends somewhat on your maximum range.

 

[std7mag]

Unless your shooting KO2M in a 50 mph crosswind, you'll never need anywhere near as much windage as elevation.
Max windage used by me so far at 1,000 yards has been about 3 minutes.