JM cloche
The outside of a [JM cloche|400px|right|thumb]
The JM cloche was an element of the Maginot Line. It was a non-retractable non-rotating cupola of steel alloy like GFM cloches, but were armed with twin heavy machine guns, as opposed to the lighter automatic rifles associated with the GFM. There were 179 JM cloches on the Maginot Line.
JM is an acronym for Jumelage de Mitrailleuses. While the MAC 31 heavy machine guns were of the same caliber as those in GFM cloches, they had a longer practical range and a maximum range of, with a 500 round per minute rate of fire.
Description
[Image:jm-cloche.jpg|The inside of a JM cloche equipped with the twin machine guns|left|thumb]The JM cloche closely resembles the GFM cloche in size and construction. It exists in three versions, all designed Model 1930: small, large and two-man. JM cloches had a single firing port, which was flanked on either side by trapezoidal observation ports. The blank rear was frequently backed by a concrete-covered embankment, which provided additional cover and reduced the prominence of the cloche.