How much does temperature effect POI?

[JohnL57]

I'm not sure if it's me, my gun or my scope, but I've had POI changes in different temperatures. In my experiences it seems as if the POI is higher in colder temps, lower in warmer temps. Perhaps the difference in air density is effecting the BC of the pellet? I'd appreciate some input.
Thanks,
John

 

[bill_dd97]

I find it to be the opposite, POImpact is lower in cold, higher in warm, as compared to weather when zeroed. I'm also above 7000ft elevation. POAim is as you described though.

 

[fe7565]

I would think the BC change would be less noticeable (measurable) than the temperature-related contraction/expansion of your stock, scope mounts, barrel relationship.

 

[zebra]

Wood and metal expands and contracts with changes in temperature. It would make sense that there would be a poi shift with a major change in the weather. I guess would be that the effect will be more pronounced with some gun designs that others, depending on how much the change in size influences the barrel. 

 

[jking]

I've noticed lower velocities in the cooler months with my Regal and the Mrod's I've owned in the past. I usually attributed it to lubes I have used in the past on the hammers that normally worked great in the summer months but can be detrimental when they stiffen up. Probably a good time to switch to a dry type lube if your using an oil based. Just an idea.
Jimmy

 

[Guest]

It is more likely your scope shifting that is causing your misranging. I've noticed with my Aeon scopes that in temps less than 55f the scope will range short. Meaning it will focus on a target and my wheel tape will read 50yds, when in reality the target is at 53, causing the pellet to hit "low". At temps above 70f the scope will range "far". Meaning it will focus on a target and my wheel tape will tell me it's 50 yards, when in reality it's only 47, and my pellets will hit high. I'm shooting .177 at 780fps juat to give you an idea of what pellet drop is like at 50yds. Plus or minus 2-3 yards is two to three clicks in one direction or another on a scope with 1/4 clicks is the difference between hitting the kill zone and not.

As for velocities I can't say, I only chrony my gun to malke sure it meets spec for my class before a big shoot.

 

[Sheharyar]

I live in a mountaneous area.I zeroed my rifle and went way up altitude on hills having Low temp.
So when I was about to take a shot boom all misses.So Height Density Temp affects the POI but don't know the exact value.

 

[Philo]

Interesting do you also think temperature would affect Windage ?

 

[Sam63]

"JohnL57"I'm not sure if it's me, my gun or my scope, but I've had POI changes in different temperatures. In my experiences it seems as if the POI is higher in colder temps, lower in warmer temps. Perhaps the difference in air density is effecting the BC of the pellet? I'd appreciate some input.
Thanks,
John

My both my regulated guns lose power in the colder temps causing POI changes.

I found this Ballistic Coefficient air temp comparison video informative. The guy put time and effort into making the video: 

 

[Bobbed06]

I had to stop keeping my pellet rifles in the air conditioning because I felt like the accuracy was reduced until the steel warmed up to the outside summer temps.