I've made a couple for my rifles. I carry them in my haversack until I need my hands free to drag a deer out. No idea if it is politically correct. I stole my pattern out of one pictured in a Dixie Gun Works catalog.
I actually loop mine over the barrel between two ramrod thimbles with the ramrod out, snug it tight, and then slide the ramrod in. Figured that was easier on the ramrod. Mine are designed to carry the rifle with it's sideplate flat against my back, so the sling ends up attaching on the side of the buttplate, not the toe.