I'm sorry I have no info about the M50 and have never seen any such simulator. Sorry I have no diagrams and little information. Versions in use in my time were as follows:
1. Simulator atomic explosion 5.5 inches. Designed to be fired from a mortar. I have no details of the filling except that it incorporated an 8 second delay composition, a charge that propelled it to a height of 400 feet, a length of instantaneous fuze and a pyrotechnic charge to simulate the explosion. Designed to be seen from a mile away, day or night. The diameter was 5.5 inches, length 7 inches.
2. Simulator atomic burst (German).
a) White DM25. 14.5 inches diameter, 22 inches high, body of cylindrical cardboard, filled with 90 Lbs pyrotechnic composition. The top had a central perforation to accept a liner, sealed in storage by a plastic transit plug. There were two rope handles for carrying. Fitted with a screw-in electric igniter DM29 with 3 feet length leads and buried flush with the ground. 100 metres safety distance required in use.
b) White smoke mushroom. Similar to the DM25, the main differences were an integral electric igniter (therefore no central hole for an igniter), web straps for carrying handles and a main filling of 70 Lbs pyrotechnic composition.
c) White DM15. Similar to the DM25 but with White smoke mushroom modifications and the filling was back to 90 Lbs pyrotechnic composition.