Re: Tikka T3 280AI project help
I am not speaking from experience here so take this with a grain of salt. The Tikka T3 in 7-08 I think comes with a 22 3/8" barrel or there a bouts, by the time you have the chamber redone and the barrel reinstalled, you are likely to lose a bit of length, probably end up around 22" I would think. I think the case capacity of the 280AI would benefit from a longer barrel, 24" would be my personal minimum here to take advantage of a higher volume of slower burning powder.
I had at one time two Remington 700 mountain rifles, one in 7-08 and the other in straight up 280. Beautiful rifles that carried well and shot accurately for what they were. Both shooting 140 Noslers over the crony they were with in 100 fps of each other, so yes you will have a velocity advantage over the 7-08, but I think that advantage will be minimal with that short barrel.
Again, I have no experience with the 280AI, just offering a thought…helping you cover all your bases. Good luck!