I will bring out a few rounds of .308 I have loaded with data from my 20" and run them over the chrono and see. I started at 2460 and ended with the last few shots around 2520, so it is speeding up.
I agree with you on that. I have one other Tikka in 6.5 and it just flat out shoots. I haven't pushed it past 550, but it holds tight. I have a buddies Ember in 6.5 PRC I'm also working up a load for and that rifle shoots like a freaking dream.
On a side note, have you ever seen an almost blued or blue sheen in your barrel? I have this blue sheen in the first 10" of the barrel.