As a former air force reservist, in a particular unit, I must
state some facts:-
1) the SP with the 0.5 HMGs is not so much for CSAR but more for
suppression fire during airmobile ( heliborne) ops. Also, to
minimise friendly fire accidents, not all SPs in a formation will
be so armed.
2) CSAR can be conducted with any type of asset in the army and air
force and even the navy. But as you can see from various TV
documentaries , you can have a "package" of say , 2 Apaches with a
Chinook, to do a CSAR mission.