Specialized Jacket sizing

chatlow

Just picked up a Specialized Element SL Elite jacket in medium from Evans. Got a medium as I'm 38-40 chest but still feels VEY snug when zipped up. Should they be pretty tight or a bit looser as I've never had a windstopper before? Guessing I will probably only be wearing a thermal underneath.

Trying to find someone selling the large, just to compare but no luck yet