Is it 1835 model,1842, or really 1816 model? Still flintlock or percussion? Fully stocked 3 bands or sporterized? Date, Springfield or other maker on lock ? Condition?
They were muskets your era was used in US Mexico War and others.
Sporters or converted percussion go for ball park 300-500 range. Fully stocked flintlock in fair to good cond will be worth between 1-2 thousand dollars.