There have been three recent (past year) episodes on this forum of failure to return to battery. One was mine. Two of these (at least) were due to the firing pin retainer being out of spec, and rotating to the side which slowed the slide (failure to feed) or trapped the slide with locking out of battery. Mine was one of those and was returned to the factory where Karl replaced the part. Should careful cleaning not prevent a repeat of the problem, consider this possibility. For pictures of the problem, look on page two of "New R9 Problem" posted by Borgers under range reports. John