Not to be "that guy"... but...might be worth putting a box through it. Give it a chance
I shot my 6.5 creed ctr yesterday and my 140 bergers shot .5" and I was a bit dissapointed.
Ive got a tikka 300 mag i bought in 2018. Planned to rebarrel it just like you. It shot 1/2" groups with barely any work up so i rocked with it. I'm finally rebarreling it to a 25 prc. Hoping on the low recoil trend and it was getting annoying single feeding it 190 berger due to the shorter action length.
The tikka barrels are damned good. And 6.5 prc vs saum is pretty apples to apples.
Also...my new 25 prc barrel is pbb's tikka lite hybrid with all the flutes. Took em ~6 months Though. Was definitely expecting it sooner.
Fingers crossed it was worth the wait