_ 50 point dakka double tap. Peak very carefully and do not expose completely ever if possible. If you do get a 'safe' poke though where you can expose your full arms, the ERML's are a nice damage amplifier. Standard engine? On a clan mech? insanity. Only do it because you have to for the slots to fit all that delicious autocannon. Sure, you could to 3xUAC5, or 1xUAC10 + 2xUAC5. But they just don't have the punch of 2xUAC10, 1xUAC5. Slow, vulnerable if team cohesion and positioning breaks down. But 100 points of dakka damage in about 3 seconds (two double taps) is pretty solid.
