Tx,
It seems there are variables that don't make sense sometimes but the best advice is as some have posted to check zero where you are hunting. Temperature can have a pretty profound effect as well. Altitude and air density (adjusted altitude) can be at longer distances something that has to be considered.
Something that has not been mentioned and is always a consideration at higher altitudes is the shot angle consideration. When we are shooting @ 600" Above Sea Level which is the "adjusted altitude" here in WV on the Ohio River shot angle is not usually a big deal.
Out West on top of a mountain @ 11,000' shooting downhill at a 30 degree angle @ 400 yards measured with a rangefinde with no compensation for angle feature if not compensated for will cause a miss. I think in some cases some do not give as much consideration here as is warranted.
Practice, practice, practice before a man heads out. When you get there early shoot @ 100 and 200 yards and check point of impact. Baggage handlers and riding in 3/4 ton trucks for 1600 miles seems to have some pretty drastic effects on POI sometimes too.
As for the windage difference discussed I have no explaination. Cover that issue with the POI check upon arriving.
Dave
