A more likely scenario is the gun was brought to the US, and maybe the original barrel was shot out, or an oddball caliber. So someone had a J. Stevens barrel that was good and fitted it to this action. If it was fitted or rebarreled at Stevens, they usually marked that info under the forearrm on the barrel. I've got a couple rifles with barrels by Stevens. One is a new Stevens barrel, and one rebored and rifled by Stevens. Both marked accordingly as re-rifled, and rebarreled at J Stevens Arms co.
