Gun and Film Geek
Yes these are 7.62mm coversions from the original 20mm Vulcan multibarreled cannon...Variable rate of fire up to 6000 rounds per minute(yes 100 a SEC)
The ac130 and AC47 gunships would be fitted with a mix of these
2 x 7.62mm and 2 x 20mm and occasionaly a 105 mm howiter thats 24,000 rounds hiting a 200 yard area every minute(and the electronics to detect a cars ignition or a radio being switched on at upto 5 miles at night in the deepest jungle...Its no wonder why the americans AVERAGED 100,000 round for every confirmed kill in Vietnam..(see John Waynes The Green Berets For an Ac 47 in action)
They now have a 25mm version fitted to war ships (phalanx) that is radar controled it tracks missiles coming in and tracks the out going rounds to adjust fire and there quicker upto 12,000 rpm some ships have 1 or 2 aircraft carriers have 4
And the recoil would Knock you off your feet so No predator or terminator 2 scenes for real.
Robbo
Film quote Green Berets
"you're what this is all about, kid"