Annulus color did mean something, even in the 8mm Lebel round, but it was apparently a fairly haphazard system until it was formalized with the adoption of the 7.5mm round in the 1920s.
According to my guide, brass/bronze colored bullets indicated ball ammunition, a blackened jacket indicated armor piercing, and a tinned (silver, I guess) color indicated tracer ammo, and a combination of varying bullet tip and primer annulus colors could mean... well, lots of different things.
As far as I know, though, the French never developed an explosive bullet for the 8mm Lebel.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.