The Sustained Rate of Fire is not a BCM spec. It is the Military USGI spec for the M16/M4/AR family of rifles. (see below)
(or google: M4 carbine sustained rate of fire)
TM 9-1005-319-23&P
Maximum rate of fire:
Semiautomatic................................................................................................................................. 45 rds/m
Burst ................................................................................................................................................ 90 rds/m
Sustained rate of fire .............................................................................................................12 to 15 rds/m
Maximum range........................................................................................... 11,814 ft (approximately 3,600 m)
Maximum effective range:
Individual/point targets (M16A3/M16A4 Rifles & Carbines)........................................... 1,641 ft (500 m)
Individual/point targets (M16A2 Rifle) ............................................................................. 1,806 ft (550 m)
Area targets (M16A3/M16A4 Rifles & Carbines).............................................................. 1,950 ft (594 m)
Area targets (M16A2 Rifle)................................................................................................. 2,625 ft (800 m)
That said, here is a awesome video:
BCM Endurance Test: Can it fire 6000 rounds with no cleaning?
Thanks for reading!