Hi Ray,
i think Tony is absolut right. The M60 was sometimes modified by SAS troopers to reduce the weight like Vladi has do it in his exelent sculpting. The forgrab was removed and the barrel was cut down. Also for better handling by firering they add a handgrip from an M-16 or SLR under the barrel. Other GPMG like FN MAG where to heavy for the conditions in Jungle Enviroment. It could be but i have no Photo seen about it that they use RPD Machine Gun´s from the enemy. I know LRRP or SOG teams use them but i think not the SASR.
Greetings
Stefan