In cleaning out an abandoned house I spied a vintage Ludwig snare case, but unfortunately it was empty. But I got lucky and the last bag of trash we took out had this Rogers Powertone snare in it, which is in great shape except for a ding in the shell between the lugs by the butt plate.

My question is about the holes above and below the throwoff and butt plate near the edges; are these factory drilled or was this a modification by a previous owner? And what purpose would these serve?

Also, any assistance dating this shell would be appreciated. Thank you in advance for your time.