Rob, Claymore; thank you both for help. I menaged to learn about exact designations of models and their scale via aurora models e-mail group archive.
"revolutionary war cannon" is in fact a 1/16 scale Gribeauval 6 pdr. field cannon with a totally distorted, caricatural barrel.
"civil war field piece" is a model 1842 12 pdr. Howitzer, again 1/16.
"Gatling gun" is one of the very late, 1890s marks for naval use; 1/16.
"75 mm World War I artillery piece" is a model 1902 3 inch US field gun. Only this is approximately 1/24.
Of the five models, the naval 24 pdr. and 12 pdr. howitzer are sound models but the Gribeauval only has its carriage which can be of use (and only with some surgery). Gatling is pretty uninteresting and basic; 3 inch gun somehow lacks detail. However, all are good bases for conversion-superdetail projects.
Thanks again for help
Don't surrender the ship !