ok guys i know that cold weather can have a fairly substantial effect on persure etc but this weekend i needed to get out to pull the trigger a bit and wanted to build up a load for a 30 Hart that i have. My question is really this if the gun stayed relatively warm from shooting and i left the ammo in the car with the heat on (for each set i went to the car took out ammo and put it in a warm pocket away from the elements), will the fact that it was 9 deg outside really hurt the process and potentially mask dangerous presure levels? My best group was prob in the low .3s if not .2s @100 towards the high end of my buildup 78gr of RL 22. There were no presure marks or signs but it was 9 out. What are your thoughts? 1) Is it a waste of time to do development in the extreme cold if i will not be likely hunting in it? 2) Does the fact that the gun and ammo stayed warm BUT NOT HOT (from shooting and from being in the warm car respectively) mitigate the effect the cold would have vs being out in the cold and shot cold bore and cold ammo?