Re: Proven 1000yd 308 bullet
You obviously will have to work up loads in your own stick to find safe levels.
In my GAP, 44.5 gr varget, BR-2s, SMK 175s and federal brass seems to work fine.
In my 5R, 44.1 gr varget, wolf primers, SMK 175s and federal brass work nicely.
In both cases, I'm using once-fired brass from fgmm, full-length resized with a neck bushing for a few thou of tension, trimmed to 2.007, loaded by ogive length with a redding seater, but comes out to about 2.815 OAL, which fits mag length in both sticks.
This is from memory, it has been a few months, and the are my sticks, this batch of components, I could be a moron or have typoed, etc. Work up from lower values to find what is safe with your rig and components, you are likely to find an accuracy node with the 175s somewhere around 2650-2700. that will get you to 1k, don't have to push any harder.
Others shooting .308s to 1k around me advocate pushing scenar 155s hard. The old sierra palma 155s (2155) aren't anywhere near as slippery as the newer 2156s, and I think the folks around me that were playing with them ended up with the scenars instead.
I've not seen a Sierra 168 at the matches that still had reliable stability at 1k, though I think one of the guys at the club was having some luck with the 168 amaxes
good luck!