Try commercial brass (Starline), CCI BR-2, 168SMK, and 43.5gr IMR-4064 at 2.810"-2.815" OAL.
I consider this load to be a clone of the 308/168 FGMM. I have also substituted the Hornady 168 HPBT Match
I am testing substituting Speer 168 Gold Dot, and will have results soon (out to 300yd).
Ballistics will be somewhat different; but it has outstanding terminal performance.
I consider the 308/168 to be a legacy round, and have no qualms about trying it at 1000yd; but then, I live/shoot at about 4300-4500ft.
For more definite 1000yd performance, I have testing with the 260 Rem/140gr Gold Dot in the pipeline.
Between Covid-19 lockdown and AZ Wildfire restrictions; getting out to shoot is a bit of a chore lately.
Greg