Get the metal cryogenically treated, I used American Cryogenics.
The process will definitely help relieve stress. Also increases wear 400%
$65 when I did it, well worth it.
Might I suggest Berger 115 grain VLD projectiles, uniform explosive performance at 50 or 500 yards.
I have a 30" Lilja Barrell and I'm getting 3248 FPS with 57 grains of Retumbo with a CCI benchrest primer, cases trimmed to .002 over minimum length, seated up against lanes and grooves but not...
I apply it after 500 rounds or so
I swab the Barrell, time it for 7 minutes
Then dry patch it
Then oil it really well with 2 or 3 patches
Then dry
Then oil again
Then continue with hoppes number 9 more
Because that copper is hiding more fouling
I'd suggest the ScoreKeeper 5 bullseye target for mathematics sake
Do a 3 day hoppes #9 soak to ensure bare bore, also some copper removal with that ammonia copper remover you only leave in for 10 minutes max
Retumbo offers "extreme" temperature proof performance
Lowered pressure
And is great with the heavier .257 projectiles.
I use a 115 grain Berger and it's been a real explosive tip from 50 yards to 500
This picture is 7 at 100
Close enough
I use Scorekeeper 5 bullseye targets
They're 1" squares, which helps when your comparing your ballistics to your actual Center Of Impact
I'm kind of a perfectionist