strange .38-40 cartridge|General Discussions & Questions|Forum|Winchester Collector

I recently came into possession of a batch of old and obsolete cartridges including some interesting calibers. Among them was a.38-40 which I did not pay much attention to until I picked it up and noticed that it seemed pretty light..It is head-stamped UMC and the primer is untouched and has the u on the primer, the odd thing is that it is loaded with a WOODEN flat nosed bullet. It apears to be a factory loading and has a long tapered crimp on it. must be some kind of dummy round, or could it have been for some kind of Gallery shooting? If anyone has any info I would love to satisfy my curiosity….brian