Actually both of mine are 3 7/8". The earlier "Performance Center" guns with the beveled barrels were known to have ignition problems due to head-spacing. Variations in .40 S&W case dimensions were blamed and several thicknesses of moon clips were offered. The later 300 "Non-PC" guns were a parts clean up and were the last L-Frame guns S&W shipped with out the ignition switch. They were cheap. Five years ago I sold one that was unfired for more than what I paid (Dealer List) for the three of them new.

Drew

PS: Be careful of the finish on the Titanium cylinders. There is a coating applied that if removed, will no longer prevent flame erosion.