My results might be similar to what you’re looking for. But I am using a Nosler 90gr Varmageddon for a Bergara B14 HMR with the 1:8” 22 inch factory barrel.
6.5 Creedmoor:
Nosler Varmageddon 90gr
Various brass (LRP), CCI BR2 primers
Speeds: 3150fps, 1981.0 FT-LBS energy - Bergara B14 HMR
CBTO 2.150” (COAL for magazine length)
COAL measurement: 2.88” max. (5rnd mag), 2.89” max. (10rnd mag)
42.0gr Varget
Fire formed headspace (Whidden tool): 1.5230”-1.5240”
This combo gave me a .390” five shot group at 109 yards. (No keyholing.) FWIW, this is a coyote load for distances between 75 and 400 yards. But with a slightly lighter bullet, the 1:8” twist does very well. Load development was as expected. After 7 charge weights, OCW was easily seen in the groupings. I found two accuracy nodes, with the 42.0gr charge of Varget being the best. I like the speed as well, although it will probably be faster in warmer weather (I did my development at temperatures between 28f and 38f).
I hope this gives you an idea of what works in the 8” twist barrel.
Edit: here’s the COAL in an ACIS 10 round mag…
I did walk this load out to 655 yards. First shot hit on an 8” gong.