On my 22-250 A.I. 26" Douglas barrel I get 3150 fps with 75 A-Max 1-9 twist
My Douglas 30" barrel I get 3420 fps same load................inches do help when using slow burning powder. Now if I use Varget then FPS only 70-100 fps difference.
Berger has determined that in .224 cal. the 1-9 twist with 75 gr A-Max or target bullets is the best for stability in flight all around.
When I shoot 80 A-Max and Berger 80 VLD's in my 22-243 A.I. with 1-8 twist they are super accurate but drift more at long range then the 75 gr bullet. Ballistics charts say and show different, but at 1000 to 1600 yds with three witness's all watching, it proved different.
I could hold dead on at 1600 yds with the 75 A-Max at 3630 fps and drift 6 feet with a 4-6 mph wind at bench. ( have no idea what wind was at 1600 yds) Then fire 80 gr A-Max and it would drift 10 feet. Fire a 90 gr bullet and even farther. I know you need a 1-7 for the 90's.
I can hit PD's at 1100 to 1200 yds just as easy with the 22-243 A.I. as I can the .260 I had or both of my friends 6.5x284.
I know this is long but I would do the 22-250 A.I. in a 1-9 twist with 30" barrel and use 4831SC or Rel 22 or 25. Shoot the 75 gr bullets.