Security Six available most commonly in 2.75', 4' or 6'. Uncommonly in 3' and 5'. Early ones had fixed sights.
Service and Speed Six's most common in 2.75' or 4' but never in 6' ( well ..... never is a LONG time but I've never seen one ).
I don't believe the Security Six was ever made in 5'. The only 5' guns I'm aware of are the RCMP Police Service Sixes.
Also, I have never seen a 3' Security Six but that doesn't mean there are none. However, the 3' tube appears with some regularity on the later Speed and Service Sixes. I think the reason the 3' is rare-to-non-existent on the Security Six is because it did come out so late in production - the Security Six was the first model dropped from production in favor of the then-new GP100 but the Service and Speed Sixes remained in production for a couple of years until Ruger got the capacity to produce fixed sight GP100 guns. So the 3' barrel appeared when Ruger already knew the Secutiy Six was being replaced, so I don't think they ever made the 3' for the Security Six (which would require a new barrel design due to the sight ramp).
There are rumors to some early frame (low back 150 prefix) fixed sight guns made with 6' barrels for export (what later became the Police Service Six was first sold as simply a fixed sight Security Six) Those early fixed sight Security Sixes appear on the earliest dealer price sheets in both .38 Special and .357 Mag as models SDA86 and SDA36 but examples are unknown and may never have been produced. By the way, the very earliest Security Sixes were adjustable sight but were simultaneously offered in fixed sight. The 2 digit guns that I have seen are all fixed sight and the earliest 3 digit that I am aware of is an SDA82 with a 3 digit SN. The first 2000 (or so) guns also had cast barrels versus later forged barrels.
The Police Service Six is most common in 4' and the Speed Six is most common in 2.75'. In the Security Six, I used to believe that the 2.75' was the scarcest but I now believe the 6' is at least as uncommon as the 2.75'. By far, the most common length for a Security Six is the 4'.
Collecting these early DA's offers up nearly as many (maybe more) possibilities as collecting old model Single Sixes as far as variations go. There were 12.25 million guns made over about an 18 year period, 3 basic models, multiple barrel lengths, several calibers, blue or stainless, pre-warning & post-warning, different grips, different sights, standard or heavy barrel, different triggers, different hammers, contract guns for police and government agencies with unique features such as lanyard rings and/or markings such as 'U.S.' and atypical model markings such as GS32N, SS84L, SS32L, foreign contract guns such as the oddball .380 Rimmed caliber, 4 different types of period packaging plus the late-ship oddballs in plastic cases or cardboard boxes with barcode labels, non-standard finishes, etc. Plus a whole myriad of aftermarket commemorative guns, some of which had at least a little factory buy-in.
So far there seems to only be a handful of collectors seriously following these guns but they are getting more and more interest all the time. Values for NIB examples have gone up quite a lot in the past decade but are still reasonable compared to collecting the guns that are more widely followed.
These DA's offer up a great opportunity for new collectors to get into Ruger collecting without breaking the bank and likely offer a higher potential for appreciation than the OM SA Rugers which have been sought after for the past 30+ years and have actually seen some recent depreciation. New 'variations' are constantly being discovered as more and more folks take notice and start paying attention to the subtle differences.
Sorry, didn't mean to go off on a rant...
