mlk18: "DOC" stands for Department of Corrections, i.e. the State Prison System. I was a LEO armorer in Nevada for years. I went to two S&W Armorer schools in the CHP Training Center near Sacramento. They have been carrying Model 4006s for such a long time that they have bought several orders of 4006s. So there will be 'several' separate groups of serial numbers applicable to their issue guns. CHP always took all new guns down and did a couple of modifications to them. I don't remember what they were, but someone on this forum will know what you should look for.

I too carried a Model 4006 for more than 10 years on duty. I agree with Mike-4; it is a great handgun and is utterly reliable. I transitioned from a Colt Model 1911 to the 4006. At first I hated the DA then SA trigger pull until I got about 500 rounds down range in two shot drills. Then I really got to like it. I was able to keep my duty gun on retirement and now it resides beside my bed wearing Trijicon night sights. ...... Big Cholla