many hammer guns were made with floating pins, normally the extractor has two curved grooves in it which pushes the pins out the way allowing the barrels to close, sometimes it it necessary to carefully re profile these grooves or just polish them ( talking the removal of tiny amounts of metal) for the extractor to properly push the pins back allowing the gun to close.

On one i have had i used heavy grease on the firing pins which stopped them falling forwards and jamming things up.