Does anyone make a picatinny rail that attaches to a single sling swivel on the forend of a bolt gun?
Welcome back! 
This is all I’m aware of. If you go that route, insure they send you the proper thread/pitch screws. HS uses different than Uncle Mikes, not sure about others.
http://www.seekinsprecision.com/index.php?option=com_content&view=article&id=8&Itemid=46