Those things are ANCIENT (the guns in the first two videos)
Made General Electric! M-134 is its military designation ~ 5000 rounds per minute.... unless perhaps it is the later model, the XM 215 which is 5.56 instead of the 7.62 of the 134.....and it puts out ~ 10,000 rounds per minute.
Your 55oRB would stay pretty busy trying to reload for either one of them.
We used to joke "back in the day" when GE had a jingle on their TV commercials: "G-EEEE, We bring good things to liiighhttt"....
Well, a few times I've been glad to see a Cobra or later a Pave Low show up with those things a blazing....
Anyway, we changed the lyrics a little; We sang the little ditty " G-EEEE... we put bad things to deattthhh!
What I can't belive though, is that sweet Sandra Bullock MARRIED that guy shooting the car in the second video!