I tested the resource, and it works. The thing is, it work only in Patriot.
local guns =
{
[470] =
{
["xPosOffset"] = 1.0,
["yPosOffset"] = 0,
["zPosOffset"] = 0
}
}
Is the definition of allowed vehicle ids (Patriot is 470), with position of the minigun on it. You can simply allow more vehicles, by providing their ids.