Scope temp shift

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josh3rd

josh3rd

Member
Apr 2, 2015
954
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Newark, Delaware, United States
If you sighted in your scope in 60 degree temperature and it's 90 degrees,is a target that is lasered at 50 yard,will it be ranged closer or farther away? I know different scopes will range more or less than others but is it generally a shorter or farther when scope gets warmer? 



Not looking for specific distance just wanted to know if a warmer scope range closer or farther.



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30 degrees, that's a pretty small temperature difference to notice any temperature difference caused scope change.

Unless your rings are REALLY wimpy (read that thin), just start over with better quality mounting rings.

Remember, the heat has to travel up through, and soak the rings...then...into the scope, THEN...heat soak the scope tube. Na, it would take more than 30 or 40 degrees with quality stuff to cause any major interior defamation.



Mike
 
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30 degrees, that's a pretty small temperature difference to notice any temperature difference caused scope change.

Unless your rings are REALLY wimpy (read that thin), just start over with better quality mounting rings.

Remember, the heat has to travel up through, and soak the rings...then...into the scope, THEN...heat soak the scope tube. Na, it would take more than 30 or 40 degrees with quality stuff to cause any major interior defamation.



Mike
Click to expand...

i think idea is that some people use parallax adjustment to "range" targets - and they are saying "some" scopes focus at different spots depending on ambient temperature.

i have never heard of this from the pb side, but then we generally don't find them (markings on the parallax knob) to be consistent enough to trust for that

- perhaps for this very reason.
 
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Scope shift is real. If you shoot fixed distances under cover or for an hour or two you won't see it. If you parallax range find it can happen multiple times a match. You also have to be aware that available light has as much if not more impact than temp. 

As for how the scope gets hot we shoot in the field, so everything is exposed to the elements, hence field target. We usually start with lower temps than when we finish. 

We also use large parallax wheels with self made range markings. Anyone who trusts factory range marks isn't going to do well.

Josh, you should takes notes of how the scope ranges each time its out, the ambient temp and scopes temp. Each manufacturer will shift differently( up/down), and each individual scope will have it's own shift ranges. Good luck.


 
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Unless your rings are REALLY wimpy (read that thin), just start over with better quality mounting rings.

Remember, the heat has to travel up through, and soak the rings...then...into the scope, THEN...heat soak the scope tube. Na, it would take more than 30 or 40 degrees with quality stuff to cause any major interior defamation.



Mike
Click to expand...

Heat soak happens from being in the sun. It's not a benchrest firearm. 

Scopes are made of multiple materials having varying thickness, and smaller gears(typicaly plastic) to make parallax wheels work. When these parts experience temp change, they move(expand/contract) at different rates. This causes ranging aberrations at least, if not full poa shifts depending on scope quality. Once everything has reached the same temp your settings will be stable, but maybe not were you started.

If you shoot from a covered bench or out of your kitchen window none of this matters. For those who shoot in the field, target or hunting it's to be considered. 
 
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