centred scopes.

[bruce moulds]

we all want our scopes to be dead centre on dead wind zero.
when changing from an nxs to a benchrest model, i set the windage the same off centre as previous, and voila bullet impact windage wise was nowhere near previous. this suggests that not all scopes are centred.
out of interest, has anyone else noticed this sort of thing?
bruce moulds.

[Barry Davies]

If each scope has it's own set of rings, then it's probably in the rings ie the relative position of the dovetail to the ring centre is a few thou different one way or the other.
Have had this problem and overcame it by remachining the dovetail on one set of rings. Considering 0.002" = 1moa on scope adjustment, it is still difficult to get both zeros the same.
If you are using the same rings for both scopes then obviously the optics of one ( or both ) are not centred.
Barry

[bruce moulds]

hi barry,
did you shit the bed too?
i was going to sleep in today, but woke up ealrier tha hoped for.
in my case it was the same rings, in the same place on the dovetail.
that's interesting about 0.002 = 1moa.
at those measurements it is possible that a little devcon in the right place could do wonders.
bruce.

[johnk]

Unless you've taken steps to ensure that your rings are perfectly aligned on the rails, then the difference can be attributed to the relatively different reaction of each scope to having the tube bent.

The floating inserts in Burris Signature Zee rings mitigate against this problem, having your rings ground or reamed in with a suitable tool then the bottom rings bedded to the scope (with appropriate release agent on the scope can work. Ultimately, you might consider purchasing a set of something like these ( http://www.benchrest.com.au/images/prod ... %20set.jpg ) to confirm correct alignment after you've trued the rings.

[bruce moulds]

john,
another approach might be to bed the bottom halves of the rings without release agent. this would offer very solid mounting.
bruce.

[johnk]

Be a bugger if you decided to move it one slot along the rail though!

[dave]

most scopes come from the factory with the adjustments centred.

this can be checked by making a simple v block arrangement to support the scopes while they are slowly rotated.

if centred, the reticle centre will remain on the object being viewed.

if not, the reticle will most likey follow a circular or oval path in relation to the object.

contributing factors to this problem can include, the inconsistencies of non concentric barrels, actions not fitted parallel to the bore, scope mounting holes drilled and positioned out of alignment, scope tubes not straight, excess mount tolerance etc etc.

in my experience, it is a deadset fluke, if when mounted, the scope centre corresponds with the windage centre of the barrel.

tapered bases, burris or similar insert rings can minimise the amount of adjustment that must be made to scope centre position. (for both vertical and horizontal adjustments).

cheers

dave

[bruce moulds]

dave,
the adjustments might be centred, but in my case it was same barrel, same mounts, same load same rifle, just different scopes.
i think we tend to put a lot more trust in what we read than we sometimes should
i had an nxs which when the parralax was removed was not in focus, yet the advertising was that they were equivalent to a top end spotting scope. a quick look through a kowa soon shot that one down.
bruce moulds.

[M12LRPV]

Just to throw another one in there. Scope graduation variation???


You said that you've swapped the scope and wound on the same windage.

That implies that the windage zero's of both scopes are known when mounted and that they returned to those known positions during the swap and that something in the adjustment resulted in the change on the target.

[AlanF]

Yes Bruce - rather than changing from one NF to another, maybe you should've changed to a better brand...

Alan

[bruce moulds]

alan,
my concern grows further.
you are sounding even more like me.
on a more serious note, yes i would like to be able to afford the big 1/8 min click schmidt, but have to make do with the humble nightforce.
bruce moulds

[IanP]

Yes Bruce - rather than changing from one NF to another, maybe you should've changed to a better brand...

Alan

Maybe it has nothing to do with the scope but is inherent to actions made in certain parts of the USA. Alan we both know that scopes on Barnard actions never have this sort of problem

IanP

[bruce moulds]

ian,
you are cause for concern too.
you are starting to sound like me as well.
perhaps it is a latent thing that barnard owners have - a secret desire to be a like a nesika owner.
bruce.

[AlanF]

ian,
you are cause for concern too.
you are starting to sound like me as well.

Bruce,

With all these Barnard owners starting to sound like you, its obvious that you have an oppressed hankering for a Barnard. You need to come to terms with this, and make an offer for one of Pestbird's.

Alan

[bruce moulds]

alan, paul and ian,
alias the "barnard brothers".
bruce.