The MAS 49 rifle was the result of several early French autoloading rifle designs of the 1930s. It was a direct gas impingement design like the Swedish Ljungman and M16, it used a tilting bolt for locking much like the BAR or FAL. The rifle was chambered for the 7.5×54 French cartridge, which was a significant improvement over the 8mm Lebel round long used in French service. With its huge rim and severe taper (thanks to a design based on the 11mm Gras black powder round), the Lebel was a difficult round to design self-loading mechanisms for.
The MAS 49 was a solid and reliable design. The most common variant was the 49/56, which was slightly shorter than the 1949 model and incorporated a grenade cutoff/sight and barrel ribbed for use with NATO standard rifle grenades.
Until we have our over set of photos taken and uploaded, you can find a very good set of internal and external photos at 50ae.net’s MAS49/56 page.