There are a lot of 600s that were rechamberd from 222 to 223. 600s in 223 were never cataloged and most of them went to Law Enforcement. I had/have one of the very few that went to civilian sales. It was delivered to the Embassy Gun Shop in Taipei Taiwan, two were shipped there and I bought one for $69. The really sickening thing was I thought it was the ugliest rifle I ever saw and had the AF armorer rip off the rib,mill off the rib studs and round off the square forend. This was 1966, who would have thought that cheap little rifle would ever be worth the money they command today.
I will say it has been an awesome rifle, even winning a informal.club bench rest match. It killed a lot of critters from gophers to deer. The barrel was finally toast and I had it rebarreled to 6x45 in the early 90s, it is stills doing its job.
From late Dec. 2022