I am just about certain that these were offered before the fire in factory TC Contender "Hunter" barrel packages for rimmed cartridges (I don't think this will work for non-rimmed) - 30-30, 357 max?, 375 Win, 45-70.
I think this would be great for a hunting gun, and could help in the event a quick follow up shot is necessary. For that reason I bought one just the other day (NIB) from M&M Trading Post - factory blued Hunter barrel in 375 Win. I checked with Ed (Ed's Contenders) a while back and he did not have any - so I kept looking until I found one, they are a bit hard to find. However, I imagine that there are some people selling them on Ebay that do not realize the barrel has that "option" and just end up selling them as standard factory Hunter barrels.