There is a 22-250 ackley that I can buy but I have no use for, it is the 40 degree version. Will a 358 winchester reamer fully clean out the chamber?

If you are thinking of having the barrel rebored and chambered to 358, I don't think it would clean up. I think there would still be evidence of the original shoulder. Generally, a used barrel for which you have no use is a barrel you shouldn't buy! GD

You don't specify barrel contour, but since you are going to throw money at this project anyway...it's not much more machine time to set the shoulder back until the chamber cleans up. The .22-250 AI is kinda old skool, which may mean it's old enough that it was built with American 4150-4140-4130 steel of the finest quality which, in one man's opinion, makes it a great candidate for re-bore. I am not, as you can see a huge fan of the stampede to stainless like 416R ..particularly the last 25 years or so of import steel, with repeated tales and pictures (affordable borescopes) of pits, inclusions, hard spots and soft spots. Now, let the howling begin, yes I know David Tubb wouldn't use anything but stainless...but I also suspect that Tubb's barrelmaker takes every precaution to assure the finest materials on earth are used (since the barrelmaker will sell a thousand barrels because 'it's what Tubb uses'). You may not get what Tubb gets.

Good question. Just measured my 22-250 Ackley & 358. On the Ackley point of shoulder is 1.540" from the base & diameter is .450" after sizing. No fired cases handy but I believe they would be closer to .460" at the shoulder. My 358 at the 1.540" mark is just a BCH short of the shoulder & measures .459" on a fired case. If you do your own work, it will only cost your time to find out, otherwise like Flintlocke says, set back a thread to be sure.

Thank you all and thank you for the measurements.