Rob, I have examined by photos of, or personally, more than 60 Dunmeyer rifles and all the carved ones except one had the familiar closed loop. On that one the carving was nearly the same except it did not have the closed loop. On page 113 of Whisker and Yantz's GUNSMITHS OF BEDFORD, FULTON, HUNTINGDON, & SOMERSET COUNTIES you will see a rifle at the bottom by Jacob Meier with carving that is similar in style to the carving on your rifle. Also at the top of the page you will see another rifle attributed to Jacob Meier that has the same patch box finial as on your rifle.
That rifle does have many Dunmeyer features. Apparently the Dunmeyers and the Meiers were close. If you google "Gunsmiths in Bedford and Somerset" you can get to the Korns family page concerning the gunsmiths. Tap on Jacob Meier and you will see another rifle with Dunmeyer features and "J. Meier, Somerset" engraved on it in script.
