You need to look at the tip to ogive measurements. A polymer tip bullet will seat different than a BTHP bullet will in the distance to the lands. A Hornady 168 BTHP has a .635" length from the tip to ogive. A 168 A-max, has a .660" length tip to ogive. So, if both bullets are seated to 2.800" COAL, then the BTHP bullet will be .025" closer to the lands. Sometimes this will help you seat the bullet closer to the lands. I try to seat my rounds using the ogive as my main measurement, but also have to stay within max COAL, especially with the 308. I can't go over the 2.800", unless I'm loading to a specific rifle and I have the rifle on hand to measure the chamber. Sometimes with a BTHP bullet, you will have to be less than 2.800", because of the shorter tip to ogive length, and may jam into the rifling. This is why I mainly load to the ogive. I have checked multiple chambers and dimensions and try to seat the bullet to a certain ogive with certain calibers. The issue with the 308 is (and other rounds, also) a SAAMI chamber has a much longer throat than a match chamber with a short throat (which match chambers are often used by gun smiths), so you have to seat the bullet to the minimum length match chamber dimensions, unless you risk jamming bullets into the rifling.
My personal 308 has a match chamber, and I chamber check all my ammo in it so it doesn't jam, or may be slightly touching the rifling (not jamming).