There was another called the 'LARCH pole' mount. The general concensus was that there was something just not quite right about sitting or standing in - or even near- the back of a truck while the convoy was being straffed. And their 20 or 30mm bullets were travelling further than your 7.62mm bullets.

The idea for small arms AA fire was as a result of lessons learned from the US in Viet Nam and the Viet Cong experience, where they concentrated small arms fire at ANY passing aircraft (on the basis that they didn't have any to shoot at.......). They caused many casualties and much damage to aircraft skins which eventually rip open.

I went on an AA gunners course at Manorbier in Wales in the 70's, shooting at a long sleeve towed behind an old silver (or was it yellow painted) jet fighter but while the tankies on the course used the .30 Brownings, we thrashed the living daylights out of GPMG/L7's/FN MAG's, call them what you will. Of the zillions of rounds fired by us and the 40mm AA guns there too, I don't think that there was one reported hit. But good fun, specially the day we fired door guns mounted in the helicopters. The hardest bit was to hold your fire until the big towing aircraft, a big fat juicy target if ever I saw one, had passed safely on its way

AA fire................. er........., maybe not with small arms from fixed mountings. But it is still taught from the waist, espcially against helicopters