Nightforce test.

[Trikstr]

Mounted a 3.5-15x56 on my 6PPC benchrest rifle today to check MOA adjustments and repeatability. Zeroed rifle at 100 yds, slightly variable wind from 6-7 o'clock .5-2 mph. Drew a 48" line up from aiming point with a level. Fired two shots and the little diamond in a 1" orange dot was gone. Clicked up 10 MOA and fired 2 more one cut the line and the other was touching just left. Clicked up 10 more MOA and fired 2 more one on each side of line. Clicked up 10 more MOA and fired 2 shots one on each side of line. Clicked down 10 MOA and fired one shot right in with last 2. Down 10 MOA fired 1 shot right in with those 2. Down 10 more and that shot was in orange dot. Dialed up 10, 20 and 30 and fired once at each and those all landed in their respective groups. Dialed down 30 and right 5 MOA and fired a shot. Dialed left 10 MOA fired a shot no hole in paper. Dialed right 10 fired one in the same hole as first. Dialed 10 left fired a shot no hole in paper. Can't figure out what happened to the 2 on the left. It was probably me but if so then that's a pretty bad screw-up. Out of ammo. Gonna clean her up and try it again in a day or two.
Measured group heights to see if they moved true MOA's. First and second groups were both .28" higher than they should have been. 3rd group was .53" higher than it should have been. The group fired for windage was off by .015" but that could be measuring error.
When my new 5.5-22x56 shows up I'll try the same test.
How common is it that adjustments are more/less than advertised? And is it common for them to change more the closer you get to the limits of adjustment range?

 

[SBruce]

Good question.

Perplexing how the 10 moa left would've missed the paper.

Dialing large amounts into the scope is still kinda new to me, but I'd be interested to hear others take on the subject too.

I hope you get some good responses.

 

[paphil]

That is a good test, one that I've done many times. First step is to get a bigger paper! Those bullets hit somewhere, it would be nice to know where. Second, I would run the turrets full range about 20 times in each direction to smooth any burrs on the threads and this also assures that the lubricant on the threads is evenly spread. Be very careful not to force the turret at either end . Most of the time this procedure will correct most tracking problems. I'm not sure why the left group would be off. Most scopes are tightening against the spring when going down or left. That is why the old Best of the West videos show the scope being turned up past the desired range and then back down to it. Most newer scopes includng the NF generally have stiffer springs that eliminate the need to do that. On the groups being a little high, a MOA is 1.047 inches. Did you multiply by 1 ", 1.04" , or 1.047". Take the group height in inches for 30 MOA and divide by 120 clicks and you will have the true click value for your scope!

 

[Trikstr]

I did use 1.047". Gonna try it again today. Paper I used was 18" wide with alittle cardboard left over on both sides. I did find another target from last year where I shot the BOX test with this scope and both shots left of center were there. Since the left 2 were present it must have been me. Box target showed some evidence of canting.

 

[davewilson]

this is a great test, and one that few scopes will pass. if you're only off .53 at 30 moa, you're better than most. and yes, i try to stay 10 moa away from either end of travel in the scope. i've heard many say their scope tracks right on, but they just mean it repeats. i do the same thing, but just shoot 2 groups, one 20 moa higher than the other. they should measure a shade under 21" apart. i have an 8-32 sightron that i've tested 4 times, and it moves the poi close to 22". Allan at sightron wanted scope, tested perfect on his collumator, or whatever it's called, then he shot it and poi was perfect. i don't want to say he's lying, but it's tuff to not believe my 4 tests. would like to hear about others doing this test and how i might be messing up.
i'm going to do this very test today with a viper HS.

 

[Trikstr]

Retested

Shot again yesterday. Looks like it was me that screwed up the other day.
Right windage was of by -.36" and left windage was +.11"of what they should have been for 5 MOA. Clicked up 10 MOA and fired once, clicked down 10 MOA and then back up 10 fired 1 shot and it was touching the one 10 clicks up. They were 10.375" high= <.095" than 10 MOA.

Which raises another question that might not be appropriate for the optics forum, but I'll raise it any way.
How of you have noticed that different lighting conditions(angle,amount) can change were you're zeroes are on target.

Gonna have buy some more match bullets.

 

[joe0121]

FWIW for high end scopes a lot of times it really helps to run through the adjustments all the way a couple times. This helps lube the mechanics inside. It sounds like this is the real issue. My NF had tracking issue out of the box and I ran through the adjustments twice it now it tracks like a Swiss watch.

 

[ultraedge]

I have experienced the same thing.On my range we shoot from north to south.As the day progresses the groups move from left to right regardless of rifle or scope used.

 

[Greyfox]

I had a Leupold that appeared to be giving issues at the high end of the elevation range. At long distance I wasn't sure if it was me or the scope. I was able to confirm this very clearly when I mounted a grid style collimator and saw exactly where the scope adjustment was inconsistent. Sent it back for repair and it was OK. This is a good supplemental check that I use with all new scopes now right out of the box. You can do a box test quite easily with one.

 

[Jon A]

How common is it that adjustments are more/less than advertised? And is it common for them to change more the closer you get to the limits of adjustment range?

It is very common, which is one of the reasons I encourage people to measure every scope they get. Even expensive scopes, if you measure carefully enough, you will often find are not exactly on as many manufacturers' tolerance is in the +/- 2% range. That doesn't sound like much, but if your scope is off 2% and it takes you 25 MOA to get to 1000 yds, you'll be off by two clicks or over 5". This is where much of the "this bullet has a higher BC in this rifle than it does in that rifle" comes from.

There are plenty of ways to do it the old fashion way shooting box tests or even not shooting:

Either way, try to do it over 10 mils or 30+ MOA at least

As mentioned above, use of a collimator allows you to do a much more thorough evaluation of the tracking without leaving your house than most anybody will go through shooting.

That is especially useful for identifying when the click value isn't constant throughout its range which you really need a huge box test to do while shooting. It's pretty normal for most scopes' clicks to go a bit crazy right at the end of their travel (lateral movement, dead clicks, etc) but you can find some scopes with click values that are different at different places in their usable travel (though it shouldn't happen on a quality scope).

 

[joe0121]

It is very common, which is one of the reasons I encourage people to measure every scope they get. Even expensive scopes, if you measure carefully enough, you will often find are not exactly on as many manufacturers' tolerance is in the +/- 2% range. That doesn't sound like much, but if your scope is off 2% and it takes you 25 MOA to get to 1000 yds, you'll be off by two clicks or over 5". This is where much of the "this bullet has a higher BC in this rifle than it does in that rifle" comes from.

There are plenty of ways to do it the old fashion way shooting box tests or even not shooting:

Either way, try to do it over 10 mils or 30+ MOA at least

As mentioned above, use of a collimator allows you to do a much more thorough evaluation of the tracking without leaving your house than most anybody will go through shooting.

That is especially useful for identifying when the click value isn't constant throughout its range which you really need a huge box test to do while shooting. It's pretty normal for most scopes' clicks to go a bit crazy right at the end of their travel (lateral movement, dead clicks, etc) but you can find some scopes with click values that are different at different places in their usable travel (though it shouldn't happen on a quality scope).

Great post. This is also why I beleive in actually confirming your drop charts at different temps. I personally believe as soon as you mount a scope you should run through the entire adjustment range twice. Then optically zero and zero the rifle. Then I would do a simple box test to see if the click are at least repeatable. Even if they are off you can factor that what you can factor is non repeatable clicks.

 

[Trikstr]

I've always been leary of the collimators that require inserting spud into the muzzle. Leupold magnetic one looked interesting, but heard they were having trouble with them initially. What would be your recommendation for a GOOD one?
Hopefully I'll get out this afternoon to test my new NXS 5.5-22x56 so that I can get it mounted up on my TRG 42 338LM.