I believe the transition from 21" tappered barrels to 23" full bull without sights happened when TC went from the original Contender to the G series. They had old stock that they continued to sell until it was gone and the Custom Shop would make you one until they were closed. The 21" with sights were some very nice, handy barrels. I'm going to start looking for and buy one more 21" barrel before I call it quits on barrels, a 7 TCU #4830. Here's a question for the experts. Did TC ever make a 21" 7 TCU barrel with two mounting lugs for the forearm or did they drop that chambering before they switched to two. Catalog # 16 shows the #4830 7TCU with one mounting lug and I can't find catalog # 17 & 18 which I'm pretty sure I had at one time.