Don't sweat the OAL number. If you intend to use this rifle as a repeater, feeding additional rounds from the magazine then you are limited by the magazine length in regards to OAL. Try the longest OAL and see if it feeds from magazine. Work up a load. Once you find the best load you could tweak it by incrementally seating the bullet deeper. .005" at a time could help you find a more accurate seating depth trend. It really depends on how much time you want to spend trying. Naturally there will be a point where the ogive of the bullet is sitting lower than the case mouth which could cause feeding and neck tension issues.
I cannot tell you any hard and fast rules. I will say that I have seen many rifles shoot their best at max magzine length limits and some that liked a seating depth deeper.
Look at this example with a 308 win. I used a Redding competition seater die and incrementally seated .002" deeper. (the numbers are just a reference number) Note that the group was open at #42 but .004"deeper at #46 it tightened it up. As the seating was moved progressively deeper the group opened up then began to tighten AGAIN. There can be more than one "sweet spot" in seating depth.
Linear Mode
