RugerSociety.com

So, I was looking over my recent 3-digit Single Six acquisition to determine whether I should reverse the safety modification. Since the safety upgrade trigger is the wider version, it looks like the Ruger shop had to open up the slot by hand on the early frame so it would accommodate the bigger trigger.
This got me to thinking about the implication of that; does the change from large ALCOA G mark to a small one coincide with the introduction of the wide trigger? That would certainly explain the casting change but I have not seen it noted anywhere. Please pardon my ignorance if this topic has been beat to death elsewhere.
It also looks like someone tried to clean it with a harsh degreaser - strictly a no-no on the anodized finish.
Here's a pic:

That is a great observation.....you might be onto something....

RENE says small ALCOA G was introduced Oct 1957.
I did not find anything about a date going to the wide trigger.....

Thanks Rod.
The REF dies not mention a date for the change to a wider trigger, Jay, but in the next paragraph it mentions minor changes, which include "...the change to a thicker trigger by at least SN 97044" which was shipped in 1958.
I've wondered why Ruger would bother to re-do the mold for no apparent reason. The two frames look slightly different in profile with the top of the inside, below the backstrap, being slightly rounded on the later frame. But that is an insignificant change and doesn't fix any known issue. And the trigger slots are different in size.
If anyone has a gun shipped in 1957 with the earlier frame that would support the idea that the thick trigger 'triggered' (sorry about that) the need for a frame modification, which has a smaller ALCOA G cast into it. Just seems logical.
Owen