Lou,
First of all, that shade of red isn't used for any Military ammunition color code in the U.S.. My guess, is that you have a "project" warhead, something that an individual performed some painting on. They stood the warhead up, and hit it with red from a spray can, getting it all over the mouth of the fuzewell. Then, they covered that with the shade of green that you have that also doesn't match any official color code. When you look closely at the ogive, you can see the red under the green.
As Jeff said, it is characteristic of older Navy stuff. The 6-1/2 Lb. warhead was used from the 50's through early 70's, but they mostly used the 10 and 17 Lb. warheads to put more steel and HE on target. The Navy ad Marine Corps sometimes come up with odd colors outside the standard color code, kind of like your older 2.75 motor that is gray. I have 5" Zuni rocket motors in white, gray, and OD green.
John