I hate to rock the boat, but I have to confess that when I read the title of this thread I started laughing. I cannot think of a single tactical application that is not better served by something other than a lever-gun. For CQB, the lever-rifle is severely out-dated by hi-cap semis in various calibers. (insert long lists of tacticool black-rifles here). For intermediate ranges, the ARs, AK derivatives (not a big AK fan here) FALs, HK91 clones etc.. seem to have it all over lever guns for any application I can think of. At longer ranges, I suppose it might be a matter of preference, though, I certainly would favor a bolt-gun over a lever action for anything over 400yds.
Sure, the lever gun was a tactical rifle back in the day. But so was the Sharps. And in my opinion, both have long been outmoded by superior modern designs for tactical or combat applications.
Now, I am an open minded individual. And it's possible that someone who's been shooting lever-guns their entire life might be more proficient and effective with a lever-gun than an AR for certain tactical applications. And, it's also possible that I'm completely missing some value the lever gun provides that a semi-auto combat rifle does not. And I'm willing to learn.