I built a test round, less primer and powder for my newly acquired 30.06. The Speer manual puts the maximum completed round length at 3.343. I seated the bullet long and smoked it over to see if it touched the rifling. It chambered smooth, without binding and the bullet did not touch the rifling. I mic'd it and read 3.409 on the dial, which is well over the max OAL. Should I be surprised that no contact was made with the rifling at this length? Wait, there's more...

Since I'm over the published maximum completed round length, should I seat the bullet to the published maximum and see how it shoots, OR, should I seat it back more than the published maximum?

Here's what has has me wondering... I mic'd a factory round and read just a shade under 3.200. With my completed round at max length of 3.343, the bullet, a 150 grain flat base spitzer, doesn't look to be in the case all that far. The round does feed into the magazine with no contact at max published length. So, should I seat it to max length, or back deeper like the factory round?

Take 'em out and shoot them...if they group well, and meet your velocity requirements...leave well-enough alone.

If they don't...then it is time to play.

I agree with Steve. Basically, there are two limitations on cartridge OAL. One is your rifle's magazine. Seat them deep enough that they don't hang up in the magazine box. The other is the length of your throat. You don't want the bullet to get stuck in the rifiling so that if you extract a live round, the bullet stays in the chamber and dumps your action full of powder!

Aside from these two factors, seat your bullets to suit yourself! OAL shown in books is only a guide (MAX industry standard length).

As mentioned above, the published OAL in any manual is that company's "recommendation." Now, just because the bullet did not touch the rifling does not mean that it isn't close enough to cause a high pressure situation. I would recommend you dish out a few bucks to buy the Stoney Point OAL gauge (or use the method described in the Sierra manual for free) so you know the exact "rifle seating depth" for any bullet you use. Also, you can't use the OAL measurement of the factory cartridge as a reference because the bullet ogive is probably different than the bullet you are using. You would need to buy another tool to measure that. If you do buy the tool, you would find out that bullet ogives even vary in the same box of bullets.