[Austin W Hogan]

Before doing anything that moves metal around, remove the barrels and forend. There is one small screw that retains the extractor/ejectors. Remove the screw and the extractor/ejectors ( no need to touch anything in the ejector mechanism, just the lifters recessed into the chamber). Clean the lifters and the passage with Hoppes on a Q tip. Clean the backs of the lifters, and the recesses in the barrels thoroughly.
Clean the locking bite in the locking lug and the barrel flats; look for a grain of powder or a shot swaged into the bite, or onto the flats or onto the water table.
Clean the breech face and the water table of the frame. Use a Hoppes Q tip and a brush to clean the recess in the frame and all the moving parts. Trip the lock release with a dowel or pencil eraser; does it release quickly? does the bolt respond rapidly? Does the bolt extend to the end of the radius in the frame that blends the breech to the water table?
Reassemble the gun and see if the looseness is gone. If not ask someone who knows their business to check the forend iron fit before doing any work on the hinge pin / hook fit. The hinge pin and hook do occassionally cause looseness but pressing the hinge pin out is a very major job; try everything else first.

Best, Austin