As subtle as a sledgehammer to a tack.
I think SG1's Richard Dean Anderson could do Calhoun.
You got the wrong SG actor (IMO, of course
)...Joe Flanigan or even Ben Browder could do Calhoun justice. RDA has the right attitude (at least close) but he's too old. Flanigan would probably be my first choice. He has the attitue, the look, and he kicks ass