nimffish, Mostly it's a cosmetic thing. All the MK IIIs shoot very well and have the same exact internal parts (except the 22/45). My personal favorite it the Bull Barrel KMKIII512. They come drilled and tapped for a scope and include a scope base. Here's mine with a set of Hogue finger-groove grips and a 2X scope mounted in the stainless Ruger ring/base. The scope comes off in seconds and the open sights are excellent.