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With handgun ammo,a change in seating depth can be significant regarding pressure.
It is different with rifle loads.
With the .308,generally,the 2.800 max overall is a magazine length issue.
A factor I look at is how the cylindrical part of the bullet is held by the case neck.With a 155 gr boat tail,you will not have enough full dia bearing surface to utilize the full length of the neck.No big deal.Say I was loading 168 gr bullets,I'd look at putting the full dia base of the bullet at the base of the neck.Its not an absolute,its a consideration.
Then there is jump to the rifling.Getting that just right seems to be one of the holy grails for the bench rest crowd..to the thousandth.So,its an accuracy tuning tool.
Remember,in some rifles,like a single shot or a bolt sporting rifle,the mag box may accept ammo longer than 2.800.
The same bullets get used in a .300 Savage and a 30-06.They have very different neck lengths.Balance this with other factors,but generally,take advantage of the neck tension/support/alignment to the degree possible.
It will vary,rifle to rifle,but with your bullet/rifle,there is a spot,it may be contacting rifling,it may be .003 off the lands,it may be .030 or .150 off the lands...the endless search.
If I recall correctly,Berger bullets discusses this topic on the web page.
Keep it fun.
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