The Falcon is an A & D action. Critical to diagnosis (but, missing in your post) is whether the gun is a single or double trigger version. If it is a single trigger, you may have an issue of adjustment or parts mixing. If it is a double trigger and you are doubling no matter which barrel, you got trouble.
Let us know. I have a double trigger,1972 vintage Falcon 12 that has been flawless. It has been seen by Cole Haugh, but, was flawless prior to that, also.
That isn't always the case, however.
Best,
Ted
