Re: Cold weather Chronograph results.
I think confirming the change with actual drops, tested at long range is a good idea. 100 fps will definitely be noticable. Having experienced so much variation with chronographs due to lighting etc. I am usually suspect, not so much with the precision of the outputs, but the absolute velocity readings. I have found Retumbo in my 6.5-284 to be very temperature insensitive, less than 20fps, with drops tested at 700-1000 yards between 0and 85 degrees. This is the temperature range I can experience during hunting season(Wyoming in early October tp Alberta in late November). IMR 4350 has given me the worst in my 270WSM with +50 FPS changes by chronograph with corresponding changes, of +7" in drops when tested at 500 yards. In my 308, Varget gives less thaen a 20 FPS difference in velocity between 30 and 85 degrees.
"Let us speak courteously, deal fairly, and keep ourselves armed and ready"-T. Roosevelt