Best parts? There's only one source of parts--Uberti. The Colt's were made with Uberti parts and finished in the U.S. The Uberti mainsprings, especially the new ones, are very good and much lighter than some of the springs they installed a few years ago. The last four Ubertis I have bought I left the stock mainspring in. Light, but still strong enough to reliably set off the caps. Yep, VTI is the place to get parts.