I have been using a 22-250 Ackley for quite a few years, now. It has the 1-14" twist and is 28.5" long.
Starting out, I settled on a 52 berger, more than satisfied with the accuracy and velocity was in the neighborhood of 4400fps with a full load of H414.
The first time I took that gun to AZ, I missed about eight coyotes, shook my head, put it away and used a different gun. Turned out that those beautiful groups at 100 yards were not making it to 200! The bullets were exploding somewhere beyond 100 and wouldn't even print on paper, at 200. Guess I didn't do ALL my homework? When I asked the guy that did the work, he claimed that he had suggested heavier bullets, but I don't remember that? From that point forward, I have been very opinionated. A 22-250 Ackley performs best with HEAVY bullets; period.
Anyway, it turned out that there were a half a dozen rifles in our little neighborhood and they were all using a 65 grain Berger, which was brand new territory for me. The BC is so much better and the velocity is almost beyond belief. I get 3925fps and it is the best coyote bullet I have ever used....and I have used a lot. Bears repeating: 3925fps with a 65gr. bullet. Steams through both sides, bang/flop. Would do the same with chucks, but it is actually too much gun for ground squirrels; not that it wouldn't work, just a waste of performance.
You can't buy the 65 any more, but they built a 64 grain mold, and I am presently using a 65 grain Starke, which Clint made for me, special. If you use the 64 Berger, don't get the MEF.
What fifty said is probably true, it is not the best choice for 800 yard live targets, but I don't go there with this gun. It's just a serious, dedicated long range coyote rifle, as good for that purpose as I have ever owned. For high volume critters, I'd consider something else, faster twist perhaps, but within the stated perameters, it will perform beautifully.
My load is 44.0 grains of H414 with the fed 210Match primer.
Good hunting. LB