Uncle Mike's Quick Detachable Fore End Band Style Sling Swivels (Blued, 1-Inch Loop) https://www.amazon.com/dp/B000O7D6IM/ref=cm_sw_r_cp_api_i_ducYEbMH7SPB5

You just need the single course thread screw.

https://www.amazon.com/Uncle-Mikes-Detachable-Swivels-1-Inch/dp/B000O7D6IM

Something like this? You can screw this into your wooden stock or they sell ones to attach to picatiny