These are pictures of my Portuguese Model 940/63 helmet.
Capacete M940 = Helmet model 940 = 1940
Capacete M/940-63 Helmet model 1940 modified in 1963.
At the moment I do not have a Model 940 in my collection.
The difference between the two models is that the 940/63 received a new liner design similar as the liner used in the American M1, its called Riddel type.
I haven't found any markings within this helmet but I was able to find this helmet has been made by
Fábrica de Braço de Prata.
Again more information on this helmet can be found on my favorit web site:
https://www.world-war-helmets.com Casque Portugais Mle 940/63
This is also interesting:
Equipamento do Exército Português