We have 4 distinct brands Fidelity Sportswear and Sterlingwear of Boston, Rothco and Alpha see http://shop.vtarmynavy.com/pea-coats-c54.aspx.
As Rothco and Alpha are made in China and not to the same standards as the first two, I'm not going to even address them.
Sterlingwear of Boston makes wool pea coats in the greater Boston area from either Wool blend or 100% wool materials. They have and have had military contracts for some time and have always told us that the cut their pea coats to the same standards as military specifications here is a link to the size charts http://www.sterlingwear.com/cart/index.php?p=page&page_id=size_chart
The problems come with the cut in the arm holes and across the chest especially for us middle aged types who have put on a few pounds. If you are fit and young and in the 32-40 inch range chances are you can go with the suggested size. Please not that coat size and chest size are two different things and see the measurement charts at the bottom for where to take the measurements. If you are bigger in the chest you may have to go up one to two sizes in the coat to get it to fit. The problem then is it may become to big in the waist. So you have consider both measurements.
Fidelity Sportswear is now just making the Wool Blend coats also in the greater Boston area. Our experience is that they tend to be cut a little better than the Sterlingwear Coats particularly in the Women's Models. Having said that most exchanges are for the next size up see chart here https://www.fidelitysportswear.biz/EZ%5CEZSizeComp.aspx
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