Headstamp question on 50 AE


I recently acquired a few 50 AE rounds with a headstamp of MRI 50:AE Does anyone recognize MRI? I suspect the “:” between the 50 and AE is also meaningful as to manufacturer of the case.

Please respond as to MRI and the probability of case manufacturer.
Thanks for any help.


Magnum Research, Inc.
The colon between 50 and AE means the case was made by Starline. The 20-round black plastic box it came in has the name SPEER, Inc. molded into the inside of the lid.


Thank you for the very quick response.


MRI stands for Magnum Research, Inc.; they make the Desert Eagle pistols.