The brighter one is a scale model of a 12-pounder, and is dated 1787, bore of model is 0.8 in, barrel weighs 17 lbs.. I'd think the "RF" monogram on the breech stands for Republique Francaise, but I'm a bit confused since I didn't think the RF existed until after 1789.
The darker one may be a model of a 24-pounder siege gun, not sure, bore of model is 0.9 inches, barrel weighs 17 lbs. It was cast in 1808. The coat of arms is that of Napoleon. Notice the surface of that tube, which was intentionally cast with a stippled surface all over, apparently a kind of non-glare surface, early camouflage.
http://s17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums%2012/?action=view¤t=e68ee455.pbw
