weather and accuracy
Hi, I'm new to this site so, I hope I'm asking this in the right section. So here's the story. I had a bad day at the range, and now i'm trying to figure out what all went wrong. I'm working up a load for 257 weatherby, federal GMM 215 primers, reloader 25 and 117 gr hornady SST... out of five 3 shot groups only 1 was respectable, .94" I know i'm not a great shot, but from a sandbag rest, i expect well under 2" minimum, more like 1 1/4 . the rifle is good for atleast .625, (best so far). it was about 18-22 degrees, kinda hard to tell with 10-20 mph wind in my face blowing snow at me. i think the worst group was about 5 or 6" it was too depressing to really measure. The good group came from 72.3 grs powder the worst was the "middle" load of 70.9 grs. I tried not to shoot when the wind was gusting, but i think a few shots may have been caught.
How much of this should i chaulk up to weather?
The reason i went out in the cold was to get a good cold weather round for Feb. hunting. It just turned out to be a little worse than i wanted it. What i'd really like to know is, does head or tail wind affect balistics as much as cross wind? And does anybody think i might have the wrong powder for the temperature? The max load didnt show any signs of pressure. I wish i had a chrono, maybe next Christmas. The reloader 25 did well with partions in 40 deg temps. I know different load.