Unknown 'cartridges'?

I aquired a box of various cartridges, many of which I am clueless about. These are the first of several I intend to post over the next few days.

About 1" long, fit properly into a .38 Special cylinder and are one piece black plastic with what appears to be a 209 shotgun shell primer in the base. The top is rounded and closed. The only opening is for the primer. Does not appear to be anything inside. No markings on any part.

What are these? What are they for?

They are blank cartridges. They have only the shotgun type primer which has enough force to split open the tip which is pre-scored on the inside. I first saw them about 15 years ago.
Usually they have no headstamp markings of any kind.

I think they actually might have a headstamp, in the form of a small raised mould number, found about 3:00 on ones I have.

Well now… you are right Pete!
With a 20x magnifier I found the number 10 on 2 and 11 on 1.
Strange blank load. Wonder why they were made this way?
Thanks for the info.

I’ve seen blanks like these used in FATS (Firearms Training Simulator) systems, where the blank causes an insert in the barrel to fire a beam of light against a screen on which a “shoot/no-shoot” scenario is being played, so a computer can pick it up and signal a “hit”.

Maxrobot - lots of these black plastic blank cartridges, made for theatrical and exhibition purposes, have headstamps beyond even the molding number. They are similar to what you picture and have an “MRA” headstamp, made by Manufacturing Research of Rockledge, Florida.