[P Flados]

Load manuals give a minimum length for one important reason. It is used to define how deep the bullet seats into the case. It is a poor measure, because they do not tell you the length of the bullet they used, but it is what they use.

For many rounds, seating a bullet a little deeper does not make a lot of difference. If you start at 10% below max for a powder charge, the extra space generated by the reduce volume of powder makes up for the difference. For many loads, there is also plenty of free space so that the reduction in free space of a deep seated bullet is a small percentage.

Now all of the above goes out the window if you get unlucky and "stack uncertainties" for the few examples that do matter. Say your are loading with a powder that spikes real bad when compressed. Say the max load listed is at 100% load density (no free space). Say that your lot of powder burns faster than normal and uses up some of that 10% starting margin. Say that your brass has only 90% internal volume compared to the cases used to develop the load. Say that you are getting +/- 2% variations on charging volume and you choose to start at 92% of max for some reason. Say that your gun is on the weak end of the spectrum for your particular round.

For a 30-06, it really should not matter at all. The case is big enough such that only slow rifle powders approach 100% load density. Slow rifle powders are pretty forgiving. Load with the bullet deep enough to chamber easily. Go the the cannelure if you want to. If you think the base of your bullet is deeper in the case than what they used, back off a little more than normal on your starting load. Work up in small increments and expect to hit your max at a little less that the manual said.

I will also second the recommendation that you should normally go to the bullet vendors web site and see what they have for load data. Using data for your exact bullet will normally avoid any confusion for proper COL. However, Hornady does not give out their 30-06 load data on the web. They want you to buy their load data manual.

Now things matter more if you were loading a case that starts out with a very small space for powder (9mm, 380, etc.). Seating too deep in these can and has caused problems.