Couldn't have said it better myself. Your loading manual will specify COL for a given bullet/cartridge....that is the number you start with. For the R700's...mine is about 0.095" from a 2.80" COL .308 175SMK round to the lands....Remington's attempt to keep us from blowing ourselves up with bullets loaded into the lands.
Respectfully disagree somewhat.
If the rifle in question is a stock Remington with a long (LONG) throat, I agree. Because you'd never be able to load cartridges long enough to seat the bullet in the lands anyway, the loading manual/SAAMI spec is a practical place to start.
However, if you have a custom, or a rifle with a shorter throat that does in fact allow you to reach the lands, my opinion is you're smart to *begin* load development seated int the lands, and work up from there. The reason, is this creates a worst case scneario for pressure, and allows you to identify a max (real max) charge for your rifle with that bullet, brass and primer combination. In contrast, if the chamber could accomodate a cartridge at 2.950", and you identifed a max pressure load at 2.900", you'd find yourself overpressure using that same charge but seating the bullets out longer to 2.950". Instead, if you identify the max charge seated into the lands at 2.950", you can safely seat the bullet deeper while maintaining the same charge**
**Disclaimer: If you really seat the bullets WAY deeper, you'll run into pressure the other direction, but it takes a dramatic change.
To more directly answer the OPs question though: There is no "max".
Consider that a stock R700 SPS (or similar) 308 chamber can accomodate a cartridge loaded with a 168smk to ~3.000" COAL. Most of these rifles will shoot the 2.810" COAL Federal GMM ammo very well, meaning your jumping that bullet ~.200".
