Scope dial up question

RDM416 · #1 10-22-2005, 05:39 PM

I spent a little time at my range today shooting 500, 600, and 700 yards. I am using a 338 Kahn topped off with a Night Force NXS 5.5X to 22X.

This is a new scope that I have only had a few weeks and have just now tried dialing up the elevation on it. In all my previous long range shooting I have used mil dots or other multi-range reticals rather than dialing up for the yardage.

I noticed that when I dial in for a new (longer) yardage that the first shot of a three shot group hits about 1 click low. The next two are dead on. This happened to me on each of 4 yardage dial ups. Is this typical? Should I go two or three clicks past the correct setting and then go back? Do I need to tap the scope to ensure it settles into the correct setting? Do I have a defective scope?

Thanks in advance for any guidance anyone out there can provide.

davewilson · #2 10-22-2005, 06:05 PM

my lupy and other scopes turn the turret out to move the cross hair to a longer distance.when i say out i mean pulling it away from the spring pressure that holds it in place.most people,even with scopes that aren't supposed to matter,always finish any adjustment by turning the knob in against the spring.this eliminates any slop in the threads,didn't quite move all the way type of conditions.this usually eliminates the "move to it's final resting place after the recoil of the first shot" condition.if you're moving 10 clicks out,turn it out 15 clicks and then back in 5. it could also be a cold barrel change in POI, but in this case i'm guessing you're not taking that much time in between rounds so it couldn't cool off that much, so i dought if that's the problem. let us know if you figure it out.

hareng · #3 10-22-2005, 06:31 PM

Firstly i would get hold of a bore sighter or collimator, this will show you whether the turret is moving or not without firing the gun. Amasing what these things show up.
If it misses or skips, send the scope back for repair.

Often tapping the turret after dialling could be worse, if it dialled correctly and tapped it could move intended range of impact!

Ankeny · #4 10-24-2005, 09:47 AM

I called Nightforce just last month and quizzed them about the issue of backlash in the threads. I won't go into a long dissertation here, but the bottom line is Nightforce's claim to fame is repeatability. They reject the notion of going past zero then back to make up for back lash and they also cringe at the thought of tapping on the scope. My NXF has been nuts reliable in repeatability. If you are unhappy, call the factory. Nightforce will make it right.

Mysticplayer · #5 10-24-2005, 12:45 PM

In this game, a scope must be reliable and repeatable in its adjustments. NO tapping, dialing this way and that. At extended ranges, the error is too great if you have a sticky scope.

Dial up, shoot, hit. If that doesn't happen, get that scope repaired or replaced.

You also have to be fair to the scope with the accuracy of your rifle. If at 500yds, you and your rifle are MOA capable, then a scope is bang on if the bullet lands in a 5" circle around your POA.

if that first shot is always outside the group, then the scope is faulty. With a Nightforce, send it back. Just make sure its not an operator or equipment error.

Jerry

RDM416 · #6 10-24-2005, 04:47 PM

Thanks everyone for your input. All of my groups were sub-moa including the shots in question. It could just be coincidence that the first shot of each group after I moved the scope setting was low compared to the remaining shots. This only happened on 4 groups so I need to get more data from addional groups. I will also try going the other direction. Dialing down as I decrease yardadge and see if my first shot is consistantly high. For now I just need to shoot some more before I start pointing fingers Night Force. Kirby built the rifle, so between Kirby and Night Force and me, I suspect the problem may be operator error. [img]/ubbthreads/images/graemlins/tongue.gif[/img]