Only for the last few months to a year has Ruger been selling their "USED GUNS" or "SECONDS" to regular distributors. And for at least the last couple of years Ruger has not marked the serial number with anything additional such as the "S", "U", asterisk or crow's foot.
Not to worry though....these guns will shoot just as intended and nothing is going to happen to them. If Ruger had felt there was something "deadly" wrong with these they would not have been released.
In most cases Ruger's "USED GUNS" or "SECONDS" had a minor blemish of some sort or were used on Ruger's factory trade show displays or used for other testing at the factory. Once used though the guns were refurbished and then shipped out....still factory "NEW".
The only collectibility problem though (yes us collectors like them when they have those extra "S", "U", asterisk or crow's foot markings) is that the box is the only thing that tells anybody it was a USED GUN or SECOND. Of course a factory letter will tell you as well, but how many people are going to call the factory on a newer made gun without the box to find out if its a SECOND?
Chet15