Question about my loads

[cj1026]

Ok so I have a Remmington 700 .308 with a 24" 5R barrel. Nothing fancy.
Last year I was working on loads. Came up with Winchester brass, CCI BR2 primers, 43.1gr of RL15 topped with a 175gr SMK. Two 5 shot groups, 82 degrees, both avg. 2660 fps with one measuring at .65 and the other at .68
Yesterday I shot the same exact load. The only change was that it was 63 degrees out. One group shot .57 and the other .58
They both avg. 2503 fps. What the hell gives?
Does a 19 degree drop in temp. affect RL15 that much?
Just sucks to be able to shoot groups like that and have them be so dang slow.

 

[wirehand]

Re: Question about my loads

RL15 is a bit of a temp sensitive powder, but that does seem extreme.

If the chrono you are using folds up make sure it flat every time or drastic changes in readings will occur.

Also the sun can screw with the sensors.

My 5R like speeds of 2630-2670 with the 175 SMK,this with a suppresor however.