Air temperature - bullet drop.

[artist]

How much effect does air temperature have on bullet drag/drop?

For example, shooting a particular load in +20 degrees C [summer], then shooting that same load in -20 degrees C [winter], what extent of difference in bullet drop/drag could one reasonably expect?

Load = .257 100gr Sierra HPBT @ 3900fps.

Rod.

 

[Louis Boyd]

I'd suggest you go to the website http://www.jbmballistics.com/cgi-bin/jbmtraj-5.0.cgi
and run the numbers yourself. Just picking one data point wont tell you much.

I'd suggest you load information which is reasonable for where you shoot and then see how making moderate changes in each parameter effects the point of impact. For example see how temperature, humidity, elevation, and bullet BC affect drop, velocity, terminal energy, and wind deflection. Also see how those items change with distance to the target for a given bullet and conditions.

 

[Dog's Elvis]

In addition to the increased "drag/drop," you may also experience, in colder temperatures, less velocity, depending on what powder you're using.