WElliott, I had also considered this to be a Samuel Glover rifle. As it happens, I always thought this piece to be my favorite Appalachian iron rifle of a handful I own. In hand the proportions are a bit more delicate than the photos allow you understand, she is long and lean, about a size 5....smile.
Louie Parker, you are correct regarding the trigger guard extension sitting on top of the trigger bar in this rifle.
I've another rifle that I haven't made available that is likely a S Glover or at least a connection to A Gross. This rifle is in amazing condition, with original finishes and raised grain still showing. There is a silver plate let into the barrel with initials that likely indicates the rifles owner.