Updated: Aug 24, 2020
This page contains all known information about the Norwegian imported Swedish M-51.
The History of the imported M-51 gas mask.
The Swedish "M-51 Skyddsmask" was used by the Swedish armed forces for most of the cold war. At some point the it also became the Norwegian armed forces main gas mask, being used by the air force and army, while the Navy most likely used it alongside Helly Hansens LFC and LFG masks. When the M-51 was adopted by the Norwegian armed forces, it was given a new designation, "NM16". It also used a complerely different carrier than the one sweden used. The NM16 / M-51 was succeeded by the FM12 (NM180) in the 90's, and the FM12 (NM180) is still issued to the Norwegian armed forces.
Norwegian - Model "M-51"
The Norwegian imported M-51 mask had a 40mm filter tread instead of the regular 60mm tread. This was due to the fact that Helly Hansen produced 40mm filters for Norway, so having a 40mm filter tread made more sense. Beside the filter tread, the Norwegian and Swedish types had no differences. The Norwegian carrier was completely different to the Swedish one in order to fit the Norwegian webbing kit.