Why do M-4s/16s have FA?

[MudPuppy]

We trained in semi auto, except in MOUT (urban ops) back in the 80s.

 

[DoubleTapDrew]

The M4 is Burst- the M4A1 is FA.
The M16, M16A1 and M16A3 are FA. The M16A2 and M16A4 are Burst.

I always thought that was odd through the evolution of the M16. It's like they kept changing their mind about whether or not the troops should have FA

 

[Pat_Rogers]

Not at all. The M4 is issued to the Big Army and Marines, the M4A1 to SOCOM. More mature, experienced etc.
The M16A3 was primarily a Navy gun. You'll have to ask them why.