Yes. Uncle Mike's don't seem to have them any more [they used to do a set with screw-on front base], but Recknagel in Germany have an extensive range of screw-on and sweat-on QD front swivel bases. Chapter 2 of their catalogue, downloadable from http://www.recknagel.de/Joomla/en/catalogue-7.html

NECG are the US agents for Recknagel. http://www.newenglandcustomgun.com/

Just received Recknagel Katalog 7 print copy last week; there's a lot of very nice bits in there!