I have an inherited Security 6 with a vented barrel. The barrel has all the Ruger lettering on it and looks unmodified . I have a certificate of authenticity and it is a GA 34 H . I am trying to determine the specifics of this piece of history and cannot make any progress. Below is a picture of the barrell. I have not seen another one like it and I don't think it was modified. Anyone have any insight into this?