Potbellied stocks are unique to m91/30 stocks. If your m27 is stocked in one of these it falls into a middle ground. Some of these are legit and there seem to be a few of these that were restocked here in the US.
I think I've seen a few pictures of M27s in pot bellied stocks that weren't M91/30 stocks.
IIRC, pot bellied stocks weren't being made until 1943, so if that is the case then your M27 sits in a wartime replacement stock that may or may not have been put on the barrelled action after the war during the refurb programs.