What year is your pistol. you can tell by the two letter code on the right side of the frame at the chamber. AC for 2003, AD for 2004, etc. There is no J. An AK is a 2009 model. Since you have A part number suffix numbers you have a fairly early pistol....AE perhaps. The original mags had no stagger slot and did not work well. They were discontinued and A suffix mags were offered with a 1" long stagger slot. These worked well until about 2006 when Walther introduced essentially the same mag but with a shorter 3/8" stagger slot. These caused jams, stovepipes and live rounds jumping out of the pistol while the next round was chambered. These were immediately replaced with B suffix mags and a return to the long slot.
So, if you have short slot A suffix mags and are having feeding issues, S&W will replace them with current magazines.
The barrel nut did not change at all, all Walther added was an O ring that fit between the threads and the main body of the nut. M1911
The magazine on the right with the short stagger slot was problematic.