I just re chambered my 26 inch Krieger 8 twist 223 Remington chamber to Ackley Improved. The chamber was originally reamed with a PTG 223 match reamer. I had increased the freebore to achieve COL of 2.565 with Hornady 75ELDM touching the lands. That accuracy load was 24.3 gr TAC with CCI 450 primer. It ran 2980 fps MV. After studying the prints, I established that it would require setting back the barrel tenon 0.020 to complete the chamber rework. I used a pilot extension to locate the reamer in the beginning of cutting. The AI chamber finished at 0.000- -0.0005, PERFECT! I fire formed my Lapua brass. Because the chamber is so close I had to remove 0.005 from the top of my shell holder for resizing the brass to a 0.001 shoulder bump. I also used the reamer to cut my Redding bullet seating die insert for the AI brass. Loaded up 30 pieces. Used 26.5, 26.8 and 27.1 gr of TAC powder, 450 primers and 75ELDM bullets seated to touch at 2.545 COL. Averaged 3123, 3168 and 3210 fps MV. My goal was to reach 3100 fps. No clickers, cratered primers. 27.1 may be getting ejector swipes but I’m not sure because this is 10 times fired brass. This is my concern. GRT predicts 27.1 to be over pressure by a few thousand psi. The most accurate load was 26.8 at about 1/4 MOA at 100 yards. The case volume increased by 0.2 grains of water from fire formed to second firing. I’m thinking I need to fire the brass at least once more to see if the shoulder gets sharper and the volume settles in. I’m about to test 26.6, 26.7 and 26.8 along with bullet seating depth. My old 223 load with these bullets liked being 0.005 jump. Any experience would be appreciated but so far I’m really impressed with the AI. By the way, at 700 yards in the wind I shot the remaining 15 rounds (5 from each load) and adjusted come up for velocity. They all landed within a 7 inch group circle and that really impressed me. More to come.