Thanks again, guys. I was thinking of Velvit Oil:

http://www.velvitproducts.com/details_velvitoil.html

I think it's an oil/varnish blend, but am not sure. Many stockmakers like the oil/varnish blends, but per Flexner, a pure varnish sounds better for a gunstock. I may experiment with blending the Rockhard and pure tung oil, but will try it on scrap first.