Yes, that one. 40 Mike Mike is a generic term for any weapon that fires a 40mm round, like the m203 or, in this case, the MK 19. The rounds, however, are not interchangeable, due to muzzle velocity, among other things. There's several units in the field here doing training. Reminds me of the days back in the seventies up until 2011, when the Armor School & the 194th left Ft. Knox. When it was here, you could feel & hear the report in Radcliff & parts of Elizabethtown, rattling windows & making the ground briefly tremor; bet it would register on a seismograph. That's how I ended up here. My father was a tanker & teacher at the armor school. (Either Skidgel or Harmon Hall, I think.) One of the many tank ranges is adjacent to Lower Douglas, where I've loved to fish for the past 40 years or so. ( It's my Walden Pond) At night, you see an orange plume, quickly followed by an awesome shock wave that REALLY shakes the ground & goes BOOM! You can feel it in your chest. You can feel the ground vibrate & see the shock wave propagate through the water. It's a blast! One of my friends years back was night fishing with me out there. I didn't think they would be practicing that night, so I didn't bother mentioning it to him. Well, turns out they were. He saw that plume & immediately said "What the fuck was that!?!" Shithead me played along with it & quickly, with a look of concern said "Oh Shit@!" Then the report. The me getting up & saying "Run!" Fastest I've ever seen him move. (Doesn't affect the fishing in the least, by the way.)