No body has mentioned mirage yet......... Where I shoot at times I am in the dirt prone, there always seems to be some mirage, on lower power settings I tend not to chase the target as much, which I shouldn't do in the first place..
If you don't have a way of calculating density altitude just use station pressure, temperature, and humidity. That is density altitude, Guestimate humidity it is a minor factor anyway.
I mainly use a chrono to find out how consistent I am reloading, consistency of a load, (es & sd) and to get a rough number to plug into my ballistic program. After that all dope is done by shooting and adjusting the program
I agree 100% with all that sterling shooter has said, and the reason for that is, I have experienced everything the OP has gone through over the last 43 years of shooting and hunting, especially with the larger caliber rifles. I can get a "little' sloppy with the pea shooters and not suffer...
If I have had too much coffee, walked a steep hill or am a little tensed up, when laying prone, I definitely can see my heart beat on the reticle. It doesn't move enough to really affect my shooting but it is there and has nothing to do with my stock, bi-pod or gun, it's all me. If I get my...