The hotter the loads got, the more the rifle liked it.
This is something I've tended to notice, but for a slightly different reason that this specifically. I've noticed my Christensen barrel will shoot identical ammo almost 100 fps faster than it shoots in my Savage 12FV. I'm honestly not quite sure why it does this.
For example:
Federal Gold Match Berger:
- Box Velocity: 2875
- Savage Velocity: 2884
- Christensend TFM Velocity: 2983
41.4gr H4350, 147gr ELD-M, Lapua Brass
- Savage Velocity: 2716
- Christensen Velocity: 2809
42.8gr RL-16, 123gr SMK, Lapua Brass
- Savage Velocity: 3002
- Christensen Velocity: 3110
42gr RL-16, 147 ELD-M, Lapua Brass
- Savage Velocity: 2796
- Christensen Velocity: 2915
These last two loads are what I developed for the TFM and are, velocity wise, quite hot, but the rifle shoots every one of these loads at better than 1/2 MOA and the two loads made specifically for it (the second load is my Savage rifle's load) shoot right between 1/4 and 1/3 MOA depending on the day.
The rifle likes hot loads, but weirdly enough it makes somewhat normal loads into hot loads for some reason. No clue why it does it, the barrel is strange. It has worked well for me, and these numbers are after 2000-3000 rounds through the tube, but it's really strange and confusing.
As far as the coldbore shot goes, I haven't yet owned a rifle that shot the first bullet exactly where the rest went. I just thought it was interesting that all of them had the same coldbore behavior of shooting slightly high right. The huge fps difference is a bit concerning on the first shot, though I know my first shot with any rifle has always been somewhat slower (not that drastic, but usually about 50 fps slower).