The "B" suffix models have a stud on the right rear of the barrel lug that engages a lever (cocking arm) at the bottom inside right rear of the action when the barrel is opened. This cocks the hammer. I would check to see if this cocking stud is there or is missing, or it is an early barrel made without the cocking stud that has been put on a later action. The early barrels for the "striker fired" models will fit late actions but will not cock the hammer. The lever may also be broken or missing. Other than that, I would be at a loss myself and have to take the gun to my gunsmith. If you have the Revised edition of my book, please see pages 90 & 91. I hope this will be of some help. Good luck!
