Why bullet seating depth is a mystery to so many mystifies me. Mark the bullet ogive with a majic marker, seat it as far out as you can and still get a good grip on the bullet, drop it in the chamber and see if it will get flush with the rear of the barrel, if not seat the bullet deeper by a half turn of the seating adjustment and try again till you get the bullet seated a half or even a quarter turn of the die adjustment off the rifling. Marking the bullet ogive with a black marker just makes it easier to see if the bullet is hitting the rifling. My 223 Superlight barrel uses an overall length of 2.355 using the 60 grain Hornady HP. No manual can give you anything closer than this method as to seating depth. If you are shooting the shorter bullets and they don't touch the rifling and they are seated out as far as is reasonable then that is what I use. Some just seat the bullet where the base of the bullet is even with the neck shoulder junction and leave it at that if the bullet doesn't hit the rifling.