Browning began a series of 22 semi autos in 1962. These semi autos carry the name Nomad, Challenger, and Medalist. Some folks call the original Challenger, the Challenger I. The series ended in 1974. Only these pistols were built in Belgium by FN. Subsequently, Challenger II, Challenger III (slab side and pencil barrel sporter) and Buck Mark Challenger were built. These firearms are, for the money, fabulous shooters with wonderful fit and finish (especially the Belgian guns). The Belgian pistols are all steel with the exception of Walnut in the Challenger I and Medalists (Nomad is quasi plastic economic grip) grips. The current Challenger BuckMark semi auto by Browning is no longer built. The later pistols are based upon an aluminum alloy. Earlier Belgian pistols in the Medalist series come in base plus tricked up variants.
ps-- These Brownings actually began life as Colt semi autos. But, that's a long story.