Hobie,

1) The reference chart on this site actually suggests it was made in 1911 (http://www.doublegunshop.com/dgsnos1.htm). That said, on the few SW's I've examined, I've never seen the Model 1911 stamp.

2) No doubt the missing letter was unintentional; kind of interesting though....there's space for the "I" but it's missing entirely, not just lightly struck.

Regarding the "Model 1911" perhaps Researcher will weigh in.