Brother loaded up some 5.56 varmint loads. We wanted an expanding bullet. There is a Nosler Varmint Ballistic Tip of approx 60+ grains.
Benchmark (being a step faster than Varget) gave excellent accuracy and velocity.
FWIW, For 5.56 ,with 1 on 9 twist 16 in bbl, Varget is my go-to for 69 gr bullets.
Point,you have good,useful powder in Benchmark. IMO, its a step "quick" for the 308 168 gr.
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a thought just occured to me,and it piggy backs on what cdoc said above
You are wanting to not waste time and components .
I get it you are trying to do a good,meticulous job for your buddy. And you are learning.
This seating depth thing ordinarily begins by establishing the LOA where the bullet contacts the rifling. That is the start point. Then our handloader might incrementally seat deeper to find as ideal distance off the lands for that rifle.
The "Jump"
We (maybe) skipped the step of finding the lands. Thats OK. With the AR-10, you have a magazine length. 2.800 is book max loa because it works through the magazine. Its got nothing to do with contacting the rifling.
I'd bet,at 2.800, the ogive of the 168 gr MK is already an appropriate distance off the lands. Thats an assumption on my part,it won't hurt to verify. But I'm pretty confident.
If you want to save components, I suggest you just load to 2.800 and go shooting.