Security Six - history & model changes ?

[Pointshoot]

Hi guys - is there an online reference that would tell the history and model changes for the Security Six that you can refer me to ? I searched on the forums and didnt find this. The Ruger company site lists serial numbers & manufacture dates, but not much more.
I'm particularly interested in what changes were made in the 151- serial number guns from the earlier ones. And, I've seen photos of Security Sixes that have pinned front sights and others without this. Was I imagining this, or did Ruger change from one type of front sight to the other ? Thanks in advance for your comments - - -

 

[RoninPA]

Depending on how serious you are about the Six series, join the Ruger Collectors Association and also join (subscribe) to the Red Eagle News Exchange. In joining RENE you get the all incusive, very detailed Reference of Ruger Firearms, basically the bible for Ruger collectors.

As far as I know, all the sights on the Six series are pinned on. I've removed sights on 150- through 162- Six series guns and they were all pinned on. Some are done so well that it looks like there is no pin. The main difference in the 150 series serial numbers and the 151 and above is the shape of the grip. The 150's (and a few 151's) have what is called the low back frame. The 151 and above have what is called a high back frame.

Here are pictures of the two different frames:
HIGH BACK


LOW BACK

 

[hittman]

Nothing available on line I'm aware of. This link below tells you about what many consider the best, most accurate, complete and reliable source available today.

Subscribe to the Red Eagle News Exchange
http://www.rugerforum.com/phpBB3/viewtopic.php?f=42&t=30544