I recently had a request for information on these cartridges from the US Navy EOD and decided I should post the basic info on the Forum. I first read about them in the Navy aviation safety magazine “Approch” in July 1971. It described both the 38 Special and 9mm rounds.
NSWC Crane Indiana developed the prototype round (Mk 123 yellow signal flare) in 1968. Below are photos of the round and some experimental bullets that came out of Crane. I have never seen a Mk 121(red signal flare) or 122 (green red signal flare)made by Crane. Crane used Remington “R-P” headstamped cases. If you look closely, you can see the residue of yellow paint on three of the four experimental bullets.
Crane contracted out manufacture of the Mk 123 to Explosive Devices Inc in Kiln Mississippi. It appears that their initial production was in 1969 or 1970 since they used Canadian IVI cases dated 1969 (two different style IVI headstamps-one with the NATO symbol and one without. Reportedly EDI wasn’t able to successfully produce Mk 121 or 122 cartridges and I have never seen either of these by EDI.
The only known Mk 121 and 122 cartridges were made by Dela Enterprises Inc, Escondido CA in 1974. These are distinctive by lacking the white tip and have cases headstamped “WCC 73”. There is also a Mk 123 round by Dela with a yellow stripe around the bullet, but I suspect it was a test only. One round is known to exist and it is in the Woodin Laboratory collection. It was reportedly picked up out of a box of similar rounds. No other examples of a Dela yellow signal flare have shown up. If anyone knows of another, please let me know.
Dela also produced plastic bullet smoke and flare loads in the late 1960s or early 1970s. These were for commercial sales and I don’t think they were ever used by the military. They also experimented with Green and Yellow rounds but only for test purposes. The tit on the end of the bullet indicate flares, the ones without the tit are smoke. These have been discussed in earlier Forum threads. Has anyone seen a green smoke round (no tit on bullet)???
I have boxes or copies of labels for a few of the Navy rounds, but would appreciate anyone with boxes for these rounds to post them.
I was very surprised when about 2005 or 2006 I was sent a copy of a Special Operations Command technical document which was on the Mk121 and Mk122 which apparently described the Dela made rounds and described them as signal rounds used by Special Forces. I have misplaced my copy. If you have or can get this document, please send a copy to me for my files.
I was surprised to see that the website https://www.globalsecurity.org/military/systems/munitions/9mm.htm shows these three signal cartridges as active items!