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CRUACH

zeroing a mil/mil scope

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Ok has anyone had issues establishing a 100mtr zero using a .1mil per click scope... for example your group being half a click from centre....... and if you were to adjust to correct then the group would be mirrored.

Any remedies? advice?

Thanks 

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1 Mil is 3.6" @ 100yds or 91.44M - 109.36Yds = 100M so 1MRAD = 99.998 (say 100)mm -  0.1MRAD = 10mm (+/5mm) @ 100M

Are you out in El or Az ?

I guess El is easier as you could put a shim under the back or front scope ring, a piece of 35mm film, or Mylar sheet would be ideal.

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1 hour ago, CRUACH said:

Ok has anyone had issues establishing a 100mtr zero using a .1mil per click scope... for example your group being half a click from centre....... and if you were to adjust to correct then the group would be mirrored.

Any remedies? advice?

Thanks 

10mm per click at 100m so you have an error of 5mm to centre?  And this is an issue why?

I bet if you loosen the scope and then re-tighten the error will be different.  0.05milrad is an extremely tiny error at the scope

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I was thinking that i'd like to be that consistent that i'd notice too  :)

 

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17 minutes ago, miki said:

1 Mil is 3.6" @ 100yds or 91.44M - 109.36Yds = 100M so 1MRAD = 99.998 (say 100)mm -  0.1MRAD = 10mm (+/5mm) @ 100M

Are you out in El or Az ?

I guess El is easier as you could put a shim under the back or front scope ring, a piece of 35mm film, or Mylar sheet would be ideal.

a piece of 35mm film stock is quite a lot of change, way more than the error reported - also shimming one ring will put the rings out of alignment (unless Optic or similar) and stress the tube

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3 minutes ago, Popsbengo said:

a piece of 35mm film stock is quite a lot of change, way more than the error reported - also shimming one ring will put the rings out of alignment (unless Optic or similar) and stress the tube

OK ... I didn't think that 0.12mm would be an issue although it is much thicker tha Mylar which comes in 25micron thick sheet.

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12 minutes ago, miki said:

OK ... I didn't think that 0.12mm would be an issue although it is much thicker tha Mylar which comes in 25micron thick sheet.

If we assume a scope is 10" between ring centres, and it's 1thou out of true:  that's 1/3rd moa error (round numbers: it's actually 20.63 seconds)

1/20th of milrad (ie half a 1/10th click) is an error of 0.0002" over 4" approximately

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21 minutes ago, Popsbengo said:

If we assume a scope is 10" between ring centres, and it's 1thou out of true:  that's 1/3rd moa error (round numbers: it's actually 20.63 seconds)

1/20th of milrad (ie half a 1/10th click) is an error of 0.0002" over 4" approximately

:)

Could it be that the OP needs to change his rings over (front to back) ?

Is it the rings/mounts that are introducing the error ??

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1 minute ago, miki said:

:)

Could it be that the OP needs to change his rings over (front to back) ?

Is it the rings/mounts that are introducing the error ??

there is no 'error' beyond the minuscule scale off a gnats nadger hair

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1 minute ago, Popsbengo said:

there is no 'error' beyond the minuscule scale off a gnats nadger hair

A good quality rail on a good quality action should (IMO) be aligned with the rifle bore. A good quality rail screwed onto the action with the correct torque should also be aligned to the bore. Good quality mounts and rings (correctly torqued) should therefore be centered to the bore. So the scopes ret (in this case) must be off center, which 'might' be possible on a Hawke or a Nikko Stirling (for example) but not so in an S&B, Swaro, March or other quality scope (i'd hope). I must admit i've never encountered (noticed) this problem.

Is this a 'real' issue @CRUACH or hypothetical ?

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Unless it is set up in a solid rifle rest and fired mechanically, surely there is no way of knowing whether 5mm error (for the centre of a group) is human error, ammo error or sight adjustment?

What are you trying to hit? If they are that small you might as well use a fly swat.

 

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12 minutes ago, miki said:

A good quality rail on a good quality action should (IMO) be aligned with the rifle bore. A good quality rail screwed onto the action with the correct torque should also be aligned to the bore. Good quality mounts and rings (correctly torqued) should therefore be centered to the bore. So the scopes ret (in this case) must be off center, which 'might' be possible on a Hawke or a Nikko Stirling (for example) but not so in an S&B, Swaro, March or other quality scope (i'd hope). I must admit i've never encountered (noticed) this problem.

Is this a 'real' issue @CRUACH or hypothetical ?

What happens if you mount your scope on a 20MOA rail?

 

The OP is off centre by 5mm, about the diameter of a 223 bullet, I wonder how many mm of the target is hidden by the thickness of the crosshair at 100yds. That could account for some of the error right there.

What size group are you getting? Anything greater than ¼" and I wouldn't worry.

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I'd rather be 5mm left or 5mm high if I had to settle for it. Mostly I'd love to be able to be able to shoot well enough to spot that kind of error consistently.

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42 minutes ago, miki said:

A good quality rail on a good quality action should (IMO) be aligned with the rifle bore. A good quality rail screwed onto the action with the correct torque should also be aligned to the bore. Good quality mounts and rings (correctly torqued) should therefore be centered to the bore. So the scopes ret (in this case) must be off center, which 'might' be possible on a Hawke or a Nikko Stirling (for example) but not so in an S&B, Swaro, March or other quality scope (i'd hope). I must admit i've never encountered (noticed) this problem.

Is this a 'real' issue @CRUACH or hypothetical ?

miki I don't think you've quite wrapped your head around the incredibly tiny amounts or error.  Everything is made with tolerances, some add, some subtract. You're absolutely correct that top quality kit is made to fine tolerances but ultimately there will be some error baked in during assembly.  The OP is identifying such a tiny error as to be unimportant.

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Thanks for the input. 
I have seen this happen using several rifles (blaser/rpa/tikka) using stalking style scopes with 1cm clicks (swaro/Schmidt/zeiss) 

for the purpose a tiny error left or right isn’t  a factor at all.
 

BUT currently I have an ATACR in MIL waiting to go on a Borden 6.5 once everything gets up and running again. I have a shred of doubt wether I should have stayed MOA for the finer adjustments?? Hence the question 

 

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35 minutes ago, CRUACH said:

Thanks for the input. 
I have seen this happen using several rifles (blaser/rpa/tikka) using stalking style scopes with 1cm clicks (swaro/Schmidt/zeiss) 

for the purpose a tiny error left or right isn’t  a factor at all.
 

BUT currently I have an ATACR in MIL waiting to go on a Borden 6.5 once everything gets up and running again. I have a shred of doubt wether I should have stayed MOA for the finer adjustments?? Hence the question 

 

I feel this is a non-issue.  I have a 1/8th moa click scope (NF Comp). I have never adjusted by 1 click only at any distance.  For windage it's a joke to think it's relevant IMHO.  For elevation,  at 1000yds the difference between 2.6" (1/4 click) and 1.3" (1/8th click) for one click is lost in the variables.  I've yet to meet anyone that can shoot a 1/4moa group at 1000yds. (yes I know it's been done and better by shooting gods of benchrest).

I think this can be extended to the MIL  - 1/10th mil is 3.6" at 1000yds - that'll do me 😁   And don't get me started on tracking errors!

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😁

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Assuming it's not the scope, and just for argument's sake, it's in any way relevant or worth worrying about (it isn't) :

5mm of error? Who did you bribe to make your loads that good?😉  5mm is well within acceptable error at 100 yds but if you must have it bang to the centre of your group allied to the bullseye, can I ask the obvious by asking "what is your group size as in number of shots to establish it?" as it's equally likely a small group is not relevant enough to draw the conclusion.  3 is statistically irrelevant, 5 is good, 7 is better.  Secondly, are you 100% sure that your ret is actually properly levelled?  If you have that a fraction off true to the perpendicular of the bore axis, there's your 5mm at 100 yds...and more.

Temperature change and pressure change alone can open up and scatter that group axis so you may find that if you went out 5 degrees either side of establishing that you have a "5mm error" it may not exist outside of the limits of your zeroing conditions.

If it's really grating at you perhaps recheck your levels using an accurate spirit level on the picatinny or mount surface for your scope and then check using a plumb line at say 20m that your ret is aligned to the plumb line when your mounting point is bang on level.  If that's off you'll always have error at all ranges.   5mm at 100 yds in still conditions is 2 inches at 1000 yds so well within the Vee-bull so really?  I'd not worry too much.  

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Zeroing at 100 yds or mtrs  is ok for starters but trajectory way too flat at this distance to think you could follow ballistics further out. 200 is a better place to nail it.

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26 minutes ago, VarmLR said:

100 yds is fine though for establishing zero.

Yes,,its just that I am thinking tjhe OP is concerned about very small and fairly insignificant amount of error at 100mtr,,,,you could zero anywhere between 80 and 140 yds/mtrs and have almost a same "zero" given trajectory is in the region of only 1/2 in/15mm or so and pretty sure this guy will want to be dialling in far greater ranges and to establish zero or what one is assuming to be zero for following ballistics from 100 yd/mtr will not get you accurately out there[unless your lucky] without checking/adjusting at suggested 200yd/mtrs and beyond.Basic stuff really just wondering whether the poster was aware.

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I'd normally advise a 100yd zero to take out most of the wind variables (a 10mph full is only an inch at 100yds), or account for them (it's easier to do at that range), then move back to 200, 300 and 400 using the same point of aim and measure the drop to the centre of each group.  That will help tune actual MV off BC (or the other way around depending on which is suspect) as well as sort out things like error from all the things discussed above.  That's usually all I'd do for establishing a zero for long range.  Everyone has their own methods that work for them.  There's an argument that the further out you establish baseline zero, the greater the outside influences which work against establishing it precisely enough, so it's basically take your pick of which you use as long as the reasoning is sound when scrutinised.

Using the method above, I can usually be fairly close to within 6 to perhaps 8 inches of a vee bull at 600 first shot in still conditions, plus or minus a handful of inches anyway.  Last outing before lockdown I got lucky and think first shot was a vee bull...I then went on to ruin things by  jumping just outside of it for the next 2 or 3!

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