A couple of months back I bought my first XP in 6,5/22-250. AFAIK it is just a 22-250 necked up to 6,5mm no other changes with the same shoulder angle. What velocities should I expect from a 14" barrel? I have been using .250 savage data to work up a load which runs at 2300fps with Norma 100gr match bullets, vithavori N150 and Lapua brass. Accuracy was 3 shots 1/2" center to center at 100m from Creedmore position with iron sights. But good can get better, so I'm wondering if N140 or N135 might be a better choice for powder. Or 123/139gr bullets.
BTW this is my 1/2 size unlimited silhouette gun

What do you experienced veterans think would help me improve even more?

Speaking personally, I'd have to develop a load using the steadiest rest possible. Bags, rest or bipod, thus eliminating the weakest link. Impressive shooting.

If your getting 1/2" groups @100 in Creedmoor, issue no need in chasing any further. I would be looking at what it does at 150 and 200. I have seen loads fall apart in that area, not a lot but some.
Jeff

One other thing, if your new to the game, recoil is not your friend. Dunno what twist your barrel is. I use a 6-223/6x45 and 60-70 grain bullets for my half size.
Not saying to rebarrel, you might look at a lighter bullet.