I have a field grade Ithaca double 12 gauge that has developed a misfire primarily on the left barral but after firing the right barrel about 20 times it will also start to misfire. It has been to three gunsmiths and no one can find anything wrong with it. It will fire for them but once I take it to the trap range "click" no boom! I am in south central PA if anyone knows a good gonsmith who is able to work on the old doubles!