The gun carriages at most of the older National Military Parks are reproduction cast iron. They were made around the turn of the last century, so most are antiques in their own right. Some of the newer parks such as Wilson's Creek only have a few guns and they are mounted on aluminum carriages.
Although most of the carriages on display look great, they may be heavily rusted on the inside (they are hollow for the most part). When I worked at Shiloh in the late 70s I saw two different carriages collapse. One that was bumped by a parked car which came out of gear, and the other that had about 10 kids crawling on it. No one was hurt fortuntely.
All the iron carriages are the same with the exception of the size of the trunnion mounts.
