Went out with some buddies yesterday. Started at 100 to confirm zero. All looked good. Shooting 77gr OTM, NF 2.5-10x24. Went to 300yds, dialed my DOPE of 1.1 which has been confirmed on this set up previously. First few shots went high, maybe a full USPSA high. Dialed back down to zero, checked DOPE, re-dialed 1.1, same result.

Based on splash above target, do some rough milling and decide to hold under 2MIL, impact on 7x12 steel. From my zero, I dial scope down 1.9MIL at which point it maxed out or hits a zero stop, (this is a second hand scope)...impact.

Confusion has entered the chat.

Cant get back out to the range for a few days to re-zero, but I read up on the concept of optical zero of the scope, maybe I need to do that.

Anyone experience this before? Ideas? This doesn't brain for my dumb ass.

I am not sure I understood everything that was going on, but I gather that the adjustments were making impacts go all over the place, including totally inappropriate from what was expected—correct?

If so, resetting the windage and elevation adjustments to the center of their travel would be the first thing I’d try. But if I understood the problem correctly, my suspicion is that the scope mount and/or rings are loose as one idea, but it could just be that the scope is bad. Nightforce does of course have an excellent reputation, but as a used scope it could have been abused to the point of being damaged. If you can’t seem to rectify the problem I’d contact NF about getting it checked and repaired if necessary.

I think in the most basic terms, I'm trying to understand how or why I need to dial DOWN to make hits at 300yds when I have a 100yd zero. I should be dialing up.

I've shot this set up out to 600 without issue. This is not my first time behind the scope. I've owned it and shot it for about 2 years, never seen this issue before.

Okay, now a little clearer for me.

Am I correct in understanding that this just happened? You dialed up to get to 600 or other long yardage in the past? If that’s so, then I cannot think of another cause other than that something has gone bad inside the scope. If the erector tube or reticle were just flopping around free, I’d expect it to be impossible to get any sort of consistent hits, but I don’t know anything about the internal mechanism of the scope.

Again, if it just started, I doubt that trying to set things back to mechanical zero will help, but I don’t know how it could hurt. To check tracking you could clamp the scope either independently or on the rifle so it doesn’t move and then check the elevation movement on a calibrated target. The might indicate if it’s not adjusting properly. Even just shaking the scope to see if anything sounds loose might tell you something.

Plus, if you are actually running out of adjustment at 1.9 mils down, then something isn’t right. On the other hand, if it’s just a zero stop issue, that’s easy enough to fix on NF scopes, or even disable it entirely. (Check the YouTube videos.) I have no use for zero stops on my Nightforce scopes and have eliminated it.

But without knowing more and being able to examine the scope myself, that’s about all I can think of. Maybe some of our other authorities can offer something else.

I appreciate your input.

Hard to tell if this just happened. Last few times I took this rig out, I only shot at 100. It's been a little bit since I shot to 300. Yes, I dialed to 600 previously in a class, which is what my DOPE is based on.

I believe the running out of mills at 1.9 down was a zero stop situation. I believe to have reset that and have full range of MILs based on the overall MIL range of this scope (per spec) and counting the elevation clicks from minimum to maximum.

If you’re not familiar how to do it (I’ve forgotten myself), there are several YouTube videos about resetting the NF zero stop (“reset nightforce zero stop”). I’m pretty certain that will necessary to reset the elevation to mechanical zero.

I’m really puzzled at this time about what could be going on, so if you get it resolved, please let us know. Perhaps even a call to NF might be appropriate.

Added: FWIW, the usual reason given for why precision rifle shooters or others who will be engaging targets at different distances by making scope elevation adjustments zero their scopes at 100 yards is that for most centerfire loads, that will require dialing up at any range other than the 100 yard zero distance. That is obviously (to me) why zero stops can be used so easily and successfully: We never dial down below the stop point.

This message has been edited. Last edited by: sigfreund,

I'm confused on this, but it seems to me the first diagnostic step is a simple tracking test or a box test at 100y. this will establish what is the mechnanical situation on the scope.

What were conditions like? Personally I am not a fan of the heaviest of .223 ammo for accuracy. Ymmv

quote:

Originally posted by old rugged cross:
What were conditions like? Personally I am not a fan of the heaviest of .223 ammo for accuracy. Ymmv

Conditions were great, nothing crazy to report.
This barrel is designed to shoot 77gr.

Quick update:

Called NF yesterday, spoke to a very nice gentleman. They were very willing to take the scope in for evaluation, they recommended some basic troubleshooting techniques, but this was perplexing (at first glance) for them as well.

I found the "optical center/zero" using the mirror method. Checked all torque settings on the mount (Bobro) and re-mounted the optic on the rifle. Shot this morning, acquired zero at 100yds, then shot at 300. Dialed my 1.1 MIL and made hits on steel.

Not sure WTF was going on this weekend, but seems to be resolved for the time being. I'll get some more rounds on it and see what happens.

Thanks for all the input.

Great! Please keep us posted.

quote:

Originally posted by MikeGLI:
I found the "optical center/zero" using the mirror method.

Neat, eh?

quote:

Originally posted by sigfreund:
Great! Please keep us posted.

quote:

Originally posted by MikeGLI:
I found the "optical center/zero" using the mirror method.

Neat, eh?

Yeah, if nothing else, I learned something new.
Any truth to the fact that it only works on SFP scopes? I saw conflicting positions online.

quote:

Originally posted by MikeGLI:
Any truth to the fact that it only works on SFP scopes?

Hmm …. That’s not something I’d ever heard.

As you may have discovered, the technique can be a little tricky to use, and in my experience works more easily with lower magnifications. That means a FFP reticle will be smaller and harder to see. But although it’s been a long time since I used the technique to completely center a scope reticle, I checked it just now with an older Leupold Mark 6 3-18× scope with first focal plane, and the few adjustments I made seemed to track as they were supposed to. That was the only scope I had readily available with an easily-removed sunshade which I also think is necessary.

Perhaps it’s just easier with SFP for some reason and that’s why people believe it only works with them.