I have Stokes/Sedley school rifle of the same vintage, 1894 action body ~20,9xx serial number. Just located south of you in Bucks county.

There were a ton of them made in the WWI era, the catalog shown was a 1918 edition. A lot of them were used by the various guard organization in WWI, as real rifles were in short supply. A lot of them were sold cheap to the users at the end of the conflict, so it is quite possible your grandfather was a gate guard, member of the state guard, bridge guard, etc and got it thorough that method.