Rudy;
Sounds as if your gun has a double underbolt in conjunction with the top cross bolt. The forward end of the underbolt bearing against the curve of the forward lug below the bolting notch cams the bols back for closing (Not all break open guns have a latch which holds the lever over to right while open). It would sound as if at some point in the linkage (or a little in all points) you have enough wear the top bolt is not being fully retracted. I hate to say it, but doubt this can be diagnosed long distance. It will simply take a careful examination of all parts to see where the problem occurs. However since you do not mention any problem with the bbl lugs hitting the underbolt, its most likely the wear is at the top bolt connection itself.
Miller
