velocity and cold weather and altitude

[30 whisper]

Hi sorry for not being on very often. I read the forum evey other night or so but no time to respond,family and those 10.5 work days no time. He some of you folks have taken some nice game this year way to go. :lol:
I have a question about how much velocity is lost at a certain temp changes is there a formula to calcutate it .
Next is there one for altituted given a certaian veloicity?
ie that is too say a 180 gr bullet at 2750 and bullet co of .507 how much is velocity effected @sea level and lets say at 3300 ft
Then same bullet same velocity @ but temp is 70 F @ 2750 now it changes to 22 F how much slow will it go on average there must be fomula out their could some let me know. Thank you very much.

 

[dakotaelkslayer]

http://www.huntingnut.com/index.php?nam ... icle&sid=3

Go to the above website and download "Point Blank" it is free software and will show you what you want to know. Also, some powders are more temperature sensitive than others...

Jim

 

[Powerstroke]

www.biggameinfo.com is also a good place to plug and play with different combo's

 

[Ol` Joe]

For ballistics, the above posts point to good sources.
The temp vs velocity question though is a bit complicated. The change varies with the cartridge, powder used, temp, altitude, and likely whether or not the moon is full that night. A good rule of thumb is Hatchers findings of 2 fps / deg F at sea level. I found this in the "NRA Fact Book" and I believe it was developed with IMR powders.