23" barrel. I sacrificed a bit. I found a good accuracy node @ 3158fps, for 105gr. I could have shot this, and had my barrel die at 1400ish rounds, possibly 1200. So what's the point ?
My opinion is this, Ackley improved can do 2 things. Run more powder for more velo, or run the same velo as the parent case for less powder, and less pressure.
If a 243 can launch a 105gr @ 2800fps with 43gr of powder, and the AI can do it with 41.5gr of powder, it's less pressure, less heat, and as a result, more barrel life.
Ackley is about increasing barrel life, not about increasing velo and killing your barrel quickly.
You want velo ? Get a 22 middlestead (which I had). Crazy good speeds, but you change your barrel as often as you change your magazine.
I've been running various AIs for the last 10 years or so. 338lapAI, 260remAI, 22-250AI, 243AI, and built many others from 6.5 obsession (6.5x55 swede AI) to 375 mini nitro (303-375british, ackley'd.)
I'm currently playing with a 6x45AI (6mm-223 AI). 80gr @ 2980fps. Virtually no recoil, easy to load, using it as a practice PRS gun for fun to see how the round works).