Actally, no. I can't think of any other Robin who has used guns offhand.
And the "Batman dealing with "heroes" who use guns" moment I like best is in the JLAvengers when the JLA are on Marvel Earth, getting the lie of the land, and Batman has been warning absolutely everybody to NOT interfere with anything that's going on as it might cause damage to the continuum.
He's in the grimmer areas of New York himself when we hear him going offline for a few minutes and when we cut back, an unconscious Punisher is tied up and hanging from a lamppost in typical Bat-style. Of course my real issue was not so much with Batman doing that (I all but cheered) but why more MU heroes DON'T!