I like to start with the bullets base at the neck/shoulder junction, if possible. If loading 223/69gr bullets, the base will be much deeper into the neck. This is ok when using a starting load and working up the powder charge.. If the bullet has little contact with the neck when trying to reach the rifling, bullets may become crooked when contacting the feed ram on chambering the round. On firing, the bullet may move before pressure is high enough to burn the power correctly. This is because of light neck tension when the COL is to long. This happens sometime, when using slow burn rates of powder in larger Weatherby type rounds. . Accuracy can be very good with the bullet jumping to the rifling in a factory rifle.