Re: Shooting on warm windy days
I shoot at a range that has 100, 200, 300, and 500 yard lines. I have seen lots of shooters that shot well at 100/200 decide to move to the longer ranges and have difficulty. While the temperature change you describe might change POI, it should not effect the the change in group size you describe. I have seen shooters overheat their barrel in hot weather and effect accuracy. Gusty wind and and mirage can definitely effect accuracy at 400 yards. A full value 8 mph wind will push a 308 in the 8" range at 400 yards, but that is 2 MOA, not 3-4. The most common issues I have seen when shooters first increase their range, assuming the rifle gave good results at shorter ranges are:
Sight picture/target aqiusition problems, they shoot at a large black bullseye target and shoot too big. Aim small, hit small.
Wind and mirage. Lots of info is available on this. Takes time and practice to master.
They use an unstable rest, or havent refined their shooting skills(trigger, hold, etc.)
which get magnified as the range increases.
They adjust their scope turrets for the longer range with a scope that has faulty adjustment response. They then get into a vicious circle of adjustment and loose concentration and zero.
If a shooter has more than one of the above going on, the accuracy problem compounds itself. It generally takes more than one session, and lots of practice to get good at longer range shooting. IMHO.
"Let us speak courteously, deal fairly, and keep ourselves armed and ready"-T. Roosevelt