cr500 said:It also depends on air density. If it is a hot day or high altitude, you can use a slightly longer bullet, but if it is cold and close to sea level ,the bullet which worked wellin summer might not work in the cold.
If you go to the JBM site (jbmballistics.com),and go to the stability section, it gives a good stability calculator depending on temperature, barometric pressure, velocity, bullet length etc.