Just received a spare 4013 single stack barrel from S&W today for my 1013 project. The original barrel will be left in 40 cal for changing back and forth. I have the 10mm finish reamer, extra power mag spring, white 10mm follower and waiting for extra power return spring. If all goes well I will ream the spare barrel and alter the mags tomorrow. Perhaps I will shorten a 4516-2 spring while waiting on the correct spring. After it functions I plan to reshape the frame and have it treated to Cerakote.