Hey thanks for getting back to me - I think you've got it. The repro vintage military label on the lining says it can be laundered (like your photo) but the modern BR label in the pocket says not -Perhaps you've got a different iteration of the jacket, but as it sounds quite weird that a garment specifically says not to wash something at all, I've queried and found this picture in this site - https://sonofastag.com/products/buzz-ricksons-m-65-combat-field-jacket-olive-drab
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"Launder with mild soap or synthetic detergents". Still quite undetailed as usually they also state washing temperature, I guess I would just wash it at 30ºC.
While I tend to agree with you that an M-65 should be able to be washed, the manufacturer might have a specific reason for these instructions. This is not the standard issue field coat, but is a reproduction. The only reason I can think of is shrinkage, but there may be others. If the coat has a trim fit as is, I would be leery of washing it.Just chuck it in the wash - go for 30 degrees if youre feeling cautious - Ive had BR and Real McCoys jackets which were supopsedly dry clean only/non washable etc and Ive just put them in the washing machine like anything else - the idea of an M-65 of all things not being up to the task of being washed is odd