Tamiya OD is (was? before they changed the colour and then changed it again) a good match for OD from the Second World War. US Army OD from the Vietnam War was in principle the same colour as in the 1940s,
but the 1968 version of the FS 595 specifications had a lighter shade of OD in the matt version only. This was most likely a mistake somewhere, because the gloss and semigloss were the same as before, only the matt was different.
All you ever wanted to know, and more, about OD :smiling3:
What this means for your model, I’m not sure about. What is the timeframe in which you want to portray it? If it’s pre-1968, then the same shade of OD as for a Second World War tank would be the right one. After 1968, you have to ask yourself when/if the tank would have been re-painted — it would have left the factory in that original shade of OD, but if you want to portray, say, an ARVN tank in the 1972 Easter Offensive, it might well have received a new coat of the lighter OD sometime in the preceding four years. At least, I assume the US delivered paint to the ARVN as well as vehicles.
BTW, the tank’s official nickname was
Walker Bulldog, not just
Bulldog. It was named after US Army general Walton Harris Walker, one of whose nicknames was “Bulldog”. He was killed in a traffic accident in Korea in 1950, and the M41
Little Bulldog (as it was known at the time) had its name changed to M41
Walker Bulldog in tribute.