[thatguy96]

The US Army is known to have tested a modification to the H-13 involving an M20 Super Bazooka in Korea. How extensive these tests were is unclear.

On Page 54 in Whirlybirds, there is mention of spraying flammable liquid from helicopters (probably using a flame thrower, also mentioned on page 54) by the USMC and then igniting it with incendiary grenades. There is also mention of troops firing small arms from helicopters on the same page. This appears to have been the extent of USMC operational use of "armed" helicopters.