I will no doubt be corrected if I am off base here, but I think that OAL is less important, as long as the round feeds and properly head spaces, than the bullet seating depth. Absent any real smarts, what I do is pull the bullets of brands that I like, measure their lengths, measure their case lengths, and calculate the bullet seating depths. I then seat the bullet I intend to reload somewhere in the range of the other seating depths in an attempt to avoid pressure issues. May just be luck, but I still have all my fingers and no ruptured guns.