Perplexing issue with NXS 8-32X56

[dstoenner]

I bought this scope off of this form back early last year. Mounted it on my Eliseo tube gun in place of a NXS 12-42 because I was running out of elevation on the 12-42 for 1000 yards. After I got it zero'd I did a tall target test to see how much elevation it had and check that it was indeed vertical. It was vertical and each 10 MOA rev gave me 10.5 inches on my target but at 3 REVs the displacement collapsed indicating I was at the end of the linear range. So for Christmas I asked for and got the new Buris XTR Signature rings. This let me add an additional 10 MOA so now I am 1 1/2 REV off the bottom. Now my ladder test showed I had 3 full REVs and 1/2 extra all linear except...

Except that the first REV went to 10.875 inches or 10.38 MOA. The second REV went to 21.5 inches or 20.5 MOA. The third REV went to 31.875 or 30.4 MOA. The third REV plus 5 MOA went to 36 inch or 34.38 MOA.

I did all of these measurements after I got home so couldn't do any thing but think about it. I needed to take this gun back to the range to do some practice so I too the ladder test back to the range and hung it up beside my practice targets. I put the scope at 22X which is the ranging magnification. Low and behold each group was right on the 10MOA marking.

So now I am really confused. How did doing the first REV add about .4 MOA and then each REV didn't add an additional .4 MOA but kept the same delta almost all the way up. When looked at through the scope I could not see the .4 MOA extra and the previous targets I did did not show this .4 MOA difference.

Some other points. This was shot indoors. I have no way of verifying the 100 yard marks but I would think these are pretty accurate. My target is beyond the 100 yard line by about 1 yard and my scope is behind the 0 yard line by about 2 yards so that is a total of about 103 yards. That would make them about 3% less in height than if it was 100 yards.

Also at the end of this test I dialed back to my 100 yard zero and fired a shot and it was in the original starting group so it returns to zero perfectly.

Hope somebody has some goo explanations because I sure don't.

One last question. Does anybody else have one of these 8-32X56 with .125 MOA clicks? According to the NF site this thing is supposed to have 65 MOA elevation but I am not getting that out of this scope.

Thanks

David

 

[mikecr]

You have collapsing MOA with turret travel.
10 moa dialed-> 10.875 IPHY-> 1.038 moa scope (you'd expect 10.47 IPHY, if an MOA scope)
Next 10 moa dialed-> produced another 10.625 IPHY-> 1.015 moa scope
Next 10 moa dialed-> produced another 10.375 IPHY-> 0.991 moa scope
Last 5 moa dialed-> produced only 4.125 IPHY-> 0.982 moa scope
The AVERAGE MOA over this range is 1.007, which I suppose supports NF merchandising, but it's a hit to varmint hunting accuracy.

If you want truly accurate MOA dialing, pick up a SFP Leupold Mk4, and shave a pound as well.
None of this matters for target shooters here. But for hunters, dstoenner is showing you a reason to test your scopes.

 

[dkhunt14]

I bought this scope off of this form back early last year. Mounted it on my Eliseo tube gun in place of a NXS 12-42 because I was running out of elevation on the 12-42 for 1000 yards. After I got it zero'd I did a tall target test to see how much elevation it had and check that it was indeed vertical. It was vertical and each 10 MOA rev gave me 10.5 inches on my target but at 3 REVs the displacement collapsed indicating I was at the end of the linear range. So for Christmas I asked for and got the new Buris XTR Signature rings. This let me add an additional 10 MOA so now I am 1 1/2 REV off the bottom. Now my ladder test showed I had 3 full REVs and 1/2 extra all linear except...

Except that the first REV went to 10.875 inches or 10.38 MOA. The second REV went to 21.5 inches or 20.5 MOA. The third REV went to 31.875 or 30.4 MOA. The third REV plus 5 MOA went to 36 inch or 34.38 MOA.

I did all of these measurements after I got home so couldn't do any thing but think about it. I needed to take this gun back to the range to do some practice so I too the ladder test back to the range and hung it up beside my practice targets. I put the scope at 22X which is the ranging magnification. Low and behold each group was right on the 10MOA marking.

So now I am really confused. How did doing the first REV add about .4 MOA and then each REV didn't add an additional .4 MOA but kept the same delta almost all the way up. When looked at through the scope I could not see the .4 MOA extra and the previous targets I did did not show this .4 MOA difference.

Some other points. This was shot indoors. I have no way of verifying the 100 yard marks but I would think these are pretty accurate. My target is beyond the 100 yard line by about 1 yard and my scope is behind the 0 yard line by about 2 yards so that is a total of about 103 yards. That would make them about 3% less in height than if it was 100 yards.

Also at the end of this test I dialed back to my 100 yard zero and fired a shot and it was in the original starting group so it returns to zero perfectly.

Hope somebody has some goo explanations because I sure don't.

One last question. Does anybody else have one of these 8-32X56 with .125 MOA clicks? According to the NF site this thing is supposed to have 65 MOA elevation but I am not getting that out of this scope.

Thanks

David

All my Nightforce scopes have more then advertised. Some only a couple of clicks and some a couple of minutes. The more windage you have dialed in a scope to get zeroed, the less elevation you will have available.

All you have to do is Mark a target at 100 yards with 10 MOA lines. Now put the gun on a bench that it can't move and click the scope 10 minutes at a time and see if the lines meet the crosshair. If you are shooting and measuring, lots of other things can be wrong. Matt

 

[dkhunt14]

Also if your gun isn't level and the scope is canted the MOA won't be right. Matt

 

[dstoenner]

All my Nightforce scopes have more then advertised. Some only a couple of clicks and some a couple of minutes. The more windage you have dialed in a scope to get zeroed, the less elevation you will have available.

All you have to do is Mark a target at 100 yards with 10 MOA lines. Now put the gun on a bench that it can't move and click the scope 10 minutes at a time and see if the lines meet the crosshair. If you are shooting and measuring, lots of other things can be wrong. Matt

Matt,

This was done indoors so my windage is just about dead center, no more than 1 or 2 MOA off of mechanical center by the dial.

Your suggestion of marking the target at 10.5 inch segments and see is good and I will try that again. When I took back my target the groups I shot ended up at the MOA lines in my reticle. My zeroing shots were right at the water line of the cross. My next 2 shots at 10 MOA were touching. So yes shooting can introduce errors but I should have seen them null out a little. Where this offset of .4 MOA is coming from is weird.

David

 

[dstoenner]

Also if your gun isn't level and the scope is canted the MOA won't be right. Matt

I have a bubble level and for this test every shot was checked for level before getting on the trigger.

David

 

[CharlieNC]

How many shots at each distance were shot to find the center? If only one shot, then its true location can be anywhere within the typical group size.

 

[KT]

David,
Get in touch with Nightforce. I'm sure they will be willing to help you. They know alot more about there scopes than any of us.
Here is there contact info.
FACTORY HEADQUARTERS U.S.A.
Customer Service, Technical & Warranty:
Nightforce Optics, Inc.
336 Hazen Lane
Orofino, ID 83544
tel 208.476.9814 • fax 208.476.9817
info@nightforceoptics.com

Hope that helps.
KT

 

[dstoenner]

How many shots at each distance were shot to find the center? If only one shot, then its true location can be anywhere within the typical group size.

For zero I fired 4 shots, 1 rev 2 shots touching and 3 shots for 2 and 3 revs

David

 

[dstoenner]

David,
Get in touch with Nightforce. I'm sure they will be willing to help you. They know alot more about there scopes than any of us.
Here is there contact info.
FACTORY HEADQUARTERS U.S.A.
Customer Service, Technical & Warranty:
Nightforce Optics, Inc.
336 Hazen Lane
Orofino, ID 83544
tel 208.476.9814 • fax 208.476.9817
info@nightforceoptics.com

Hope that helps.
KT

Yes I know that nf will repair my scope if it is indeed faulty but I am trying to if anyone else has seen something like this and what was the resolution if any.

Thanks

David

 

[ronemus]

You should be shooting at least 5 shots (preferably10) at each setting so you can identify the group centers. Two shots touching that happened to both be high leave you scratching your head about the cause of nonlinearity that wasn't there. Elevation and windage are set using threaded pistons acting on an optics cell; any nonlinearities due to the length of the cell (it really traces an arc defined by the pivot point and its distance from the turrets) will be very small.

 

[dstoenner]

As a follow up, I have to say, with egg on my face, what I thought was an issue, isn't. :-(

I thought this over and felt that if I were to call Nightforce that I needed to be a sure as I could there was an issue. So I felt I needed to do this one more time, just to be sure.

This time I did pretty much what I did last time but I did double check each step along the way. I even used the same load as last time. 107 SMK with 46 gn IMR 4350 in Hornady cases with BR-2 primers. I also shot 3 to 4 shots at each stop along the way.

When I got home I measured everything. 10 MOA on the scope yielded 10.032 MOA on target. Even at 30 MOA on the scope I had 30.375 MOA on target and 20 MOA was 20.250, in between. That is a 1% error at most.

So I am now confident that all is good with the scope and the perplexing was me not my equipment.

Thanks everybody for chiming in.

David