Originally Posted by L-S-R
It is the sidewheel parallax mechnism that is being affected. The POI is not effected.
Snipers have spotters, laser rangefinders, satelite co-ordinates, intelligence info for exact weather conditions etc.
For us the parralax mechanism determines the range, if this shifts in temperature we either under range and miss low or over range and miss high. E.G. a 55yrd target measured with tape in 30degrees, with scope you range it 59yrds dial accordingly and dink high, if you had used your 55 yrd setting you would have the correct elevation for the target.
In a really bad case both the gun and the scope are affected by temperature, then you are really in trouble
Heat can cause guns to run faster and cold slower which would only exaggerate your difficulties in varying temperatures with a scope thats parralax mechanism varies with temp change.
This is of course IMO and there will be other more knowledgeable people along to help.
Hi, it is not only the mechanism that gets affected. The light refraction (some scopes worse than others) can also cause this to happen. Have a look at the attached pics. This scope was mounted on a table in an airconditioned office. The scope was not touched. A tripod was set up behind the scope with the camera on it. The poi shift was purely relating to the direction the sun is shining from on the target
Btw the manufacturer is replacing this scope (new nikko) as it is not supposed to happen. I believe it happens in all scopes. some worse than others. This makes it important to get your scope optically zero'ed imo.