Shooting my Series 70 GCNM this past Saturday in a match. I had several failure to chamber fully, could be time for a good cleaning. What concerns me is that 6-8 times when this happened, the hammer would fall when I pulled the trigger. This was with the slide perhaps 1/8 to 3/16 inch from being closed. I could then recock the hammer, tap the back of the slide and be back to shooting. What direction should I look? I bought the pistol used, with very few rounds through it. As far as I know it is stock in all regards. I have fired perhaps 1500 rounds of 230 RN lead, loaded to around 750 fps.