The crewman by the Lynx in the last picture is holding a British made Accuracy International AW50 which is 50 cal. The Coast Guard Rifle is a 50 cal as well but I'm not sure what type.
The machine-gun is to "wake them up" and the 50 cal to disable the engines. Very effective.
Well done to the RN crew.
Farmpilot, if you want to shot pigs out of your helicopter there's plenty of Kiwi's and Aussie's on this site who will give you advice!