Is there a model number on the gun somewhere. As others have said the 30-30 was not introduced until 1895 and was marked 30 WCF instead to 30-30 on many early guns. I used www.armscollectors.com
and came up with 1884 as well. this does not seem possible. A few more details and perhaps a picture may help.
Marlin has made some special runs of rifles that do not fit into the normal code. It is possible that you have a more modern rifle that was a special run.