An important consideration when rechambering from a standard to an Ackley chamber is the need to set the barrel back, usually a complete thread so the writing, sights, etc. are all facing up. If the Ackley reamer is run in until the old chamber is cleaned up there will be excessive headspace when firing factory ammunition. The go gauge becomes the no-go gauge & if a go gauge is required will be approx. .004" shorter than the standard go gauge.
I have to smile when people that have never owned one regurgitate what they've read or heard. I've worked extensively with 4 different Ackley chamberings & each one has been just a wee bit different. Two of them (257 Roberts & a 30-06) fireformed factory brass without a hitch. The 3rd one (338-06) even though chambered properly as noted above refused to do so, developing that bright ring at the web that tells us the base will soon separate from the body. Brass was successfully formed with 16 gr. of Unique, a case full of cornmeal & a wad of TP fired straight up into the air in the backyard. I dont know why, but it's how that rifle worked out. This chamber is a tad rough... bolt lift is fine but extraction isn't so good, so that could be part of the problem.
The 4th (22-250) was a trade-in & apparently just had the reamer run in to clean up the chamber (& then some) giving somewhere between .020 to .035" excess headspace. Brass was partially separating on the 1st firing, so now is expanded from .22 to .25 then resized in a standard 22-250 die with a secondary small shoulder to chamber very snugly & fired with a stiff standard 22-250 load. This one is not a true Ackley. It's an Ackley long maybe. Using Ackley dies kept way off the shellholder I'm just now retiring some 30 year old brass that was loaded 10 or more times (a 53 gr @ 3975 fps), that's finally age-splitting necks. Primers still fit snugly.
I like all of my Ackleys & run them on the warm side, because that's what they do best. If primer pockets stay tight for 4-5 (or more) firings it works for me if the accuracy is good.
