The Chauchat was famously widely regarded as a terrible machinegun.

At the moment WW1 broke out, unfortunately conditions in France were that in practical terms it was this or nothing for light machineguns. The French had already saddled themselves with the 8mm Lebel, and this machinegun design was the only one they had ready to go.

The gun in 8mm Lebel needed the half moon shaped magazine because of the cartridge’s extreme taper. The spring had to follow that shape to function, and that’s big ask. The magazines were also thin, making them easy to dent. A dent could stop up the follower or spring. The cutouts in the side are obvious problems in mud, made worse by the rounds being oiled which would attract grime.

In 30-06 the half moon shape of the magazine was gone as were the cutouts. The magazines were still thin and fragile. I believe there were many complaints (I have no source at this exact second) about failure to extract caused by the higher pressure of 30-06 not working well with the hasty redesign of a not great to start with design.

In both cases the design and production quality of the magazines was a big weak point.

Somehow a quarter million of these guns were made, and used by many countries. Some countries even used them into the 1930s, though I think that’s more indicative of militaries, especially cash strapped ones, holding on to anything they own. The U.S. and French both quickly ditched their Chauchats (with the French also ditching 8mm Lebel) as soon as alternatives became available.