Have you been on a Rocky Mountain high again my friend?
You mean the OAL listed in manuals can be ignored? Always?
Long ago, in a far away land when large toothed creatures and demons ruled the darkness OAL's published in loading manuals were minimum OAL which corresponded with their published pressure data. (They may still be published as minimum OAL as far as I know... I don't pay any attention to them. Yes I know, I'm a bad boy.)
Reloads can easily be produced, (safe and accurate) without the use of calipers as long as one learns the basics of loading and the principals behind it.
There are several of us lurking around here, and many, many elsewhere that loaded for years without owning calipers simply because we couldn't afford them and learned how to load without them. My first caliper was a plastic one from Lyman, (still have it, Little Stevie and Zombie Steve have seen it although I didn't let Zombie touch it 'cause it would have ended up in pieces), and had the accuracy of a smoothbore musket at 500 yards.
As I mentioned before and as Fred has harped on since the day before they invented dirt, published OAL's, (except for minimums for safety sake and even those can be a mere guide if you know what you're doing), mean absolutely nothing since they will always be barrel or cylinder specific.
Oh, and I'm always on a Rocky Mountain High, just like John Denver... although it didn't work out all that well for him.
Jack