Maybe I will have to get my own borescope and try focussing it ...

I would love to know what makes a barrel good or dud... Savage factory barrels are rough as guts but a few still shoot well anyways. I had a 223 that was super accurate but a 7 twist and blew up noslers, but not other brands. From which i surmised the factory barrel was scoring the jackets and noslers had thin jackets, bad combination. Sierras shot a treat !
The way that truflight behaved i also suspected some stresses that caused movement as the barrel heated giving elevations, but at that stage my elevation issues could easily have been caused by bag setup hence i was unsure. My setup has improved but i am still confused by all this .....