I've got a 20 ga U1 DeHaan (Huglu O/U) that has a problem with the upper barrel firing pin when shooting doubles. It seems like on the first or second pair when I shoot for the first time of the day or after the gun has sat for a while, the first barrel (lower) shoots fine, but the second shot (upper barrel) doesn't allow the trigger to get pulled. There is some resistance and then the pin finally engages, usually well after the bird is past. After that, the gun works normally. The pins are titanium and I haven't taken them out for cleaning, because I don't know how, but I've shot cleaning stuff into them from the receiver end and blown out the residue. It doesn't seem to be dirty but I don't know if it's the pin or the trigger. Any suggestions?