Navy Body

[cyberi4n]

Guys, I've just taken delivery of a lovely G&P M4 QRF - which has what's classed as the "Navy" body. Try as I might, I've not been able to find out why it's refered to as the Navy Body, although I notice that it has bullet images rather than text on the fire selector etc. Can someone explain why it's referred to as the navy body, and where that definition comes from, etc etc?