Ruger did make an alloy frame single six.
Here's a link describing it.
http://www.gunblast.com/Hamm_Single-Six_Lightweight.htmMy old Blue Book Of Gun values says they were 4-5/8" barrels, made 1956-1958, 200,000-212,000 serial number range, so there were 12,000 of them.
100% $500
98% $400
95% $300
90% $250
80% $200
70% $175
60% $150
Add $100 if all blue with blue alloy cylinder
Add 100% for verifiable factory second ("S") marking.
Interestingly enough, Colt also made a Frontier Scout .22 SA with the alloy frame from 1957-70 and the values are identical to the Ruger...but Ruger made it first.
Ka6otm