I have been doing load development at 500 yards for 6-7 yrs, and have shot some nice test groups with custom chamberings. But the best group I have ever seen shot at 500 came about a month ago, Bergara B14 6 Creedmoor, this was after a 60fps velocity drop and trying to bring the load back. The group was under a half inch, so if you subtract bullet dia, it was tight.
I have yet to see a Bergara that does not shoot well.
I do feel on our test subject barrel, that the barrel steel is soft though, I have never seen a barrel exhibit such throat wear. Way excessive for the rd count, and the guy does not warm it up. I will continue shooting 10 more rds while his cools off, i have the luxury of grabbing a 2nd rifle when he is ready to resume.