I'm trying to work up a load for a 243 and I'm not getting anywhere near the velocity I should be. What am I missing. First things first. Chronograph readings are consistent, (within 30 fps). I'm using Varget, Winchester brass, Remington primers, Remington 100g core lokt bullets. All rounds had a COL of between 2.652 and 2.658. I started with the following loads of 31.4g, 32.2g, 32.8g and 33.7g. The load data I have lists 33.7 as the max load with a velocity of 2838fps. I weighed each charge to make sure I was consistent. The heaviest loads averaged 2452fps. Could cold weather mess with the velocity that much (in the 20's)? Barrel length is 22". The only thing I didn't do was shoot a factory round over the chronograph. I plan on doing that tomorrow as well as shooting the heaviest loads again. Am I missing something obvious?
Thanks for any help.