Issued RAF Bomber Jacket

Sizes run very small and tight

I normally run a 40R and so I sized up to an XL. Received a 107 Regular, which in US is between a 40-44R. It fits okay but still runs quite a bit small. When wearing I have John McCain arms that can't be raised above my head. Not AP's fault of course, but I suspect these jackets have been shrunk at some point during their service life.

I sized up like they said and it was still very small as i was unable to extend my arms fully after putting it on

Fits very true to size, I wear a large hoodie and it fits perfectly.