Here are three weapons related stories:
1) This happened in Viet Nam. A fully loaded AH-1 was awaiting take off instructions. It had a full compliment of FFARs and a full ammo box. On this helicopter the ammunition was fired electrically and grounded squibs fired the rockets. A large Air Force Transport (C-141) or C-130 had just landed and was taxiing into the hardstand. His RADAR was on and as he turned into the taxiway the RADAR beam painted the AH-1. The electromagnetic field was so strong that it fired all of the FFARs, which flew down the runway and exploded off the base and at the same time, all of the electrically fired ammunition exploded taking both pilots and the helicopter out in an instant.
2) The Iranian Government purchased a large number of brand new AH-
Js, which supposedly had been well proven in the service of the US Marines. Many maintenance related defects were uncovered and the first time they fired the cannon it showed that this element of the design was not fully proven. When the gun was fired the muzzle blast severely damaged the skin under the nose of the helicopter and it blew open all the inspection panels under the forward end of the fuselage. This problem was eventually solved by redesign of the muzzle break on the gun.
3) The Iranian Government contracted with the Germans to build and place into operation an ammunition factory. One of the ammo types made in this factory was used in the AH-1Js cannon. The major portion of the ammo used up to that time was drawn from US Army supplies and the Iranians wanted to use their own ammo. An AH-J was loaded with the locally made ammo and went out to the firing range. This was the first test of the ammo as the Germans never tested it in a fixed weapon and the Iranians never tested it in a helicopter mounted weapon. When the gun was fired several rounds went out of the muzzle as intended but then as each barrel turned and fired the round jammed in the barrel and then there were several more coming down the chute. The gun exploded and severely damaged the helicopter.