The cylinder has no markings and there is only one (that I am aware of). 22 Cal Single-Six' so I assume it is 22LR. Ill have the gun in hand either this weekend or early next week - its being. A call to Ruger left THEM confused - theyre reviewing the pics and their docs, too.

002' (thousandths) larger in diameter for the 'new' Magnum cartridge. Hey everybody, Im trying to find manufacture date for my Single Six and coming up short. Serial number seems to match the old Single Six from 1971 or so. and thus was never meant to be a 'convertible' ass the 22 magnum did NOT come to being until 1959, when the bore became. Welcome to the forum, good info above and yes its a very nice early 'flategate) RSS5,, the name meaning the loading gate on your gun ( the early guns ) was made ' flat' so as to not be confused with a Colt ( that has always been MY take on the reason 'why') but soon to be found that was hard on the fingernails to open it to load and unload.a company called Premiere, made a replacement, rounded, loading, a bit longer that what was to be the 'standard or norm' so Ruger did their own and was used from then on, sometime in 1957.nice gun, and the hard rubber (plastic) grips on your gun have turned to a shade from brown due to sunlight ( ultraviolet rays) or maybe even just getting 'dry'.wipe them down with a good oil or grease and the may darken up.many folks 'like' this brown shade.another thing to keep n mind is being your gun is a very early one, the bore diameter is on the smaller ( tighter) side.