I can think of two approaches off-hand.
1. You have the surname Palmer in your tree. This line is not complete but the presumption is that one of your Palmer ancestors is related to the inventor or was the inventor of the Palmer Musket. You need to build this line to find out.
2. Perhaps you had a revolutionary War Ancestor who recieved a Palmer Musket and passed it down through the family. You would need to demonstrate that they served in a unit that recieved the Palmer Musket. Perhaps more research around the Musket and who actually used them?
Of course there are other various on these but right now both of them require that you to build out the rest of your tree from Molly.