This rifle was likely built sometime after the War of 1812 as it is fitted with a "G. THOMSON" lock which were manufactured in the 19th century in Washington, Pennsylvania. As you will note it has a waterproof style pan , a roller frizzen, and light border designs.
It is signed "A. Schweitzer" in hand cut script on the top of the barrel.
The patch box is rather similar to the Melchior Fordney Lancaster School rifle seen in "The Kentucky Rifle" by Merrill Lindsay and also has similarities with the Abraham Schweitzer rifles in "Gunsmiths of Adams, Franklin, and Cumberland Counties Pennsylvania" by James B. Whisker.
This is not surprising given that Schweitzer married Fordney's sister and lived in Lancaster before moving to Antrim Township in 1804 and then to Chambersburg from 1805 to 1823.
Matching attributes on this rifle and the other Schweitzer rifles, include the crescent moon cheek piece inlays, the rounded toe plates, and the simple carved scrolls below the low combs, standard Chambersburg style molding and a German silver thumb plate.