I've heard it's a VC-smell detector. Might be internet fuddlore but apparently it's made to detect the scent of charlies, but it didn't work very well.

Looks like a flame thrower. Probably activated when it caught the smell of charlie.

I hear tell he was in Jim "Going Mental on the Oriental" Webb's Alpha Fucker Six team.

His code name was Charcoal.

>>17894
XM-2 Personnel Detector
In the rather deadly game of “hide & seek” played by the US Army and the Viet Cong led to a rather bizarre technical innovation during the Vietnam War: the people sniffer. The detection technology was developed by General Electric for the US Army’s Chemical Corps. “People Sniffer” technology was based on locating hidden enemy troops by detecting the chemical traces of urine and sweat. The sweatier or more piss-soaked that the VC were, so much the better for the People Sniffer, if not so much the operator! https://www.forgottenweapons.com/accessories/xm-2-personnel-detector/

The first version of the People Sniffer was the XM-2 personnel detector man-pack (also known as the E63 man-pack personnel detector). The XM-2 consisted of a backpack-mounted sensor, coupled with an air intake tube mounted on the end of a M16 rifle. Deployed during 1967, reports are that the XM-2 was often a bit too sensitive, and would only pick up the sweat odors of its user. This, coupled with the rather loud “ticka-ticka-ticka” noise that sensor made while in use rather gave the whole game away. Understandably, troops were uncomfortable carrying a heavy noisemaker into an ambush zone. So the XM-2 man-portable system gave way to the much more powerful XM-3 airborne platform, normally mounted on a helicopter. The XM-3 delivered much better results, although the Viet Cong eventually learned ways to deceive the device’s ability to detect sweat, urine and campfire smoke.

If you can find an XM-2 “personnel detector” out there somewhere, it will make a great accessory for your vintage M16A1 rifle—granted you can find one of those.

  U.S. soldier with E63 personnel detector, receives maintenance assistance from another soldier in the field. https://youtu.be/ZdHyKPTHgVs

A US Army 1st Air Cavalry Division soldier equipped with an E63 personnel detector manpack, advances through a jungle area during training in Ankhe, South Vietnam. He signals to his buddy, that his E63 is malfunctioning. He assumes an alert defensive posture, as his buddy opens the manpack and checks its internal components. Interior view of the E63 shows air transport fan and chemicals. Location: Ankhe South Vietnam. Date: February 1, 1967.

  US Army 1st Air Cavalry Division soldier with an E63 personnel detector, in Ankhe, South Vietnam. https://youtu.be/4kGpf9W5s3c

A US 1st Air Cavalry Division soldier equipped with an E63 (XM-2) personnel detector manpack. The E63 intake tube is mounted to the barrel of his M-16 rifle and a signal cord runs from the backpack to a speaker under his helmet. The soldier advances slowly through an area of heavy brush, during training in Ankhe, South Vietnam. Another soldier moves in the background. Location: Ankhe South Vietnam. Date: January 31, 1966.

I prefer this Vietnam War-era personnel detector.

Inexpensive to produce, but the training costs are high.

I just realized I have a photo of the inner workings

But does it also detect bombs and drugs, cure HIV/AIDS, or find lost golf balls and broken water mains?
https://en.wikipedia.org/wiki/ADE_651
http://mashable.com/2014/02/26/egypts-miracle-hiv-device/

What about heart-beats?
http://www.pitt.edu/~kconover/dkl.htm