Eric, Scott, others and I have wondered about this fine rifle. It is so similar to several rifles by Wm Antes - stock pattern or profile, mounts and carving behind the cheekpiece. It is easy to wonder where it was made and by whom. Richard on that link mentioned Nazareth vs. Lancaster and ca 1790. It is fun to speculate.
Abraham Henry was sent from Lancaster to Nazareth to learn the gunstocking trade with his brother Wm, Jr. Wm, Jr also traveled back and forth to Lancaster to visit and care for family members, so Lancaster style and perhaps mounts would have been familiar to both. We only have a signed pair of pistols to illustrate Wm, Jr.'s work - perhaps he was stocking in the Lancaster style. Henry Albright later came to Wm, Jr at Nazareth (to learn either gunstocking or the joiner trade), so connections to Lancaster abounded. Later Abraham was party to contracts for large numbers of arms, probably subcontracted some work, and may have supplied barrels with his name to satisfy terms of contracts. Wm Antes apparently developed his gunstocking skills in the area north of Philadelphia with the early Bucks County gunmakers. Antes later moved with family to Westmoreland County, and may have had connections to Lancaster.
There is at least one more "Lancaster rifle" with this same rotated carving design behind the cheekpiece. Though they did not have the internet and auction photos for comparison, they were better connected and informed of others' work than we assume. Bob