Put a spot of grease less than the size of a pea in each hinge pin socket. And coat BOTH surfaces where forend iron meets receiver real well. Maybe a slight amount on the two flats on each side of the barrel block.
Clean it all off real well after shooting and you’re ready to go again. cls
One thing to avoid is the semi-popular idea of using oil instead of grease. The theory is that if oil can protect engines from metal transfering between parts that are moving quite fast and under a lot of heat and pressure, it ought to do a great job on a break-open gun. I posed that question to Krieghoff International a few years ago and was told that oil will not work on a gun because in engines, there is an oil pump that constantly flushes those moving parts with filtered oil. There is no pump in a gun, so the oil film that you put there eventually wears through.