hey, im a newish to the long range game. thanks in advance for any comments/suggestions. im working up my skills from being seasoned a 0-300m hunter to something more of a 500m shooter with my tried and tested rig. 22"barrel weatherby vanguard, boyds thumbhole stock bedded floated wearing a leupy vari 1 2-7x33 (simple but effective!) shooting factory 130gr rem corelokt protected points. this combo usually shoots .25MOA groups sighted 200yd zero, (usually can 3 leaf clover on a dime at 200gun)) the other day i did a range session 10mph 6oclock tailwind, hot day 85deg and a dancing vertical mirage. my 100 group was about right 1.5" high, 200 group was tight but 3" low, my 300 group also tight but was even lower 15"low ! i reshot the groups several time over a couple of hours, a new one on me? i was working my way out to 400-500, but couldnt get past the wildly low trajectory i was experiencing. could this be tailwind mirage, or a horizontal parralex error effect from my cheeck position on my stock? other suspect is a new batch of factory rounds being alarmingly cooler than they should be ? open for suggestion.