More interesting is the gun with no moving parts. All electronic, it can be configured a lot. Good for combat situations (no dirt, weapons oil etc) if they (somehow) manage to a) make it work properly and b) shieldthe electronics. Water/grit and electronics really don't mix.
Downloaded the video of the 40 mm. Only saw a single round being fired from each barrel, so there's no telling whether it really works from that video.