I ordered one of these in an XXL.  I referred to their sizing chart and I normally wear a XXL (19in neck, 50 in chest, and 35 in sleeve)... but this thing fits me like a tent.

I had previously ordered some Rothco pants in a large that are supposed to fit 36"-39" waist (I wear a 36-38) and they were too small in the thighs and really snug (fit, but barely) in the waist.

What this tells me is that the Rothco sizing chart is a total waste of time, and in order to return the shirt they are making me pay for the shipping to return them.  So on top of paying $30 for a shirt that doesn't fit, I had to wait 2 weeks for them to get here... and now I'll have to pay $10 top ship it back (!?!?!?).

Bottom line is... I'm done with these vultures...  I can go to my local surplus shop and get the same thing for the same price without having to deal with all of the BS that comes from ordering gear on the internet.