original field officers overcoat?

[Richtofen]

hi, my grandpa just passed away on saturday and i got this overcoat that was his, he once told me it was an officers overcoat and doing reseach it appears to be the field officer overcoat style however its not made in the olive drab material mid and late war ones are made in and it lacks any official US markings, that being said it does have the ww2 style officer buttons,the shoulder board areas look like something may have been put on at one point, it has an early 40's conmar zipper, it has an old style laundry tag (whether army or not i dont know) and it also has my grandpas name stenciled into it and the zip in liner (i only show a few letters of this for privacy reasons), I believe it may have been a private purchase or custom made one he had done as he was a 2lt in the CAP and not official army, the belt it comes with also appears to be the officer overcoat belt style only made from leather, whether original to the coat or not i cant confirm 100%, i would love any help there is in figuring if this coat is actually military or if its just a fancy civilian one, thanks!