[oger]

I just picked up a 4in 150 prefix Security-six that is fixed sight. Is this a common item it is the first I have come across.

 

[Neon Horse]

Perhaps. Pics make it more fun!
Congrats on the new 6!

 

[oger]

Will see what I can do, not really setup for pictures.

 

[REB]

A fixed sight marked Security Six would indicate an early production revolver. Ruger later renamed the fixed sight version the Service Six to differentiate it from the adjustable sight Security Six.

I would say its not that common.

 

[Argee1950]

I agree with REB...the fixed sights were designated Service Six or Speed Six.

 

[REB]

I found a note on these that the name change for the fixed site version changed around the same time the grip frame was changed from the low back to the high back. The high back guns are prefix 151 and up.

 

[bwinters]

it is an early one. later called service six.