The 8mm Lebel Cartridge
When it first appeared, the Lebel's 8×50R smokeless ammunition allied to its longer range and flatter trajectory brought a revolution in infantry armament. A soldier equipped with a Lebel could outrange troops carrying rifles chambered for blackpowder, large-caliber lead-bullet ammunition. Using smokeless powder, he could remain virtually invisible to an enemy at longer ranges, yet locate an enemy at any range by the smoke from their rifles. He could also carry more cartridges for the same overall weight. In the M1886 Lebel rifle, the early 231 gr (15 g) jacketed flat-nosed, lead-cored Balle M flat-nose bullet had an extreme range of 3,500 yards and a muzzle velocity of 2,000 ft/s (610 m/s), with an effective range of approximately 438 yards (401 m).
A new 197 gr (12.8 g) solid brass pointed (spitzer) and boat-tail bullet ("Balle D") was adopted for the Lebel rifle in 1898 and placed in generalized service after 1901 - the very first boat-tailed plus spitzer design bullet adopted by any army. Desaleux's "Balle D" provided a flatter trajectory and increased the extreme range of the Mle 1886 rifle to about 4,000 yards and its maximum effective wounding distance (when fired indirectly at massed area targets) to 1,800 yards. More importantly, the realistic effective range of the 8mm Lebel was increased (due to the bullet's flatter trajectory) to approximately 457 yards (418 m) using open sights. The altered ballistic trajectory of the new cartridge necessitated a replacement of the Lebel's rear sights.
In order to avoid accidental ignition of sharply pointed Balle D ammunition inside the Lebel's tubular magazine, a circular groove was formed on each case head, around the primer pocket, in order to receive the bullet tip of the cartridge that followed. The spring-loaded follower inside the tube magazine was also redesigned in 1898 to accommodate the new Balle D bullets. Lastly the Berdan primer itself on each French military Balle D round was protected against accidental percussion by a thick, convex primer cover that was also crimped in after 1912 (Balle D "a.m.", for amorcage modifie (modified primer)). This disposition provided in effect a double primer cup. Because of this double thickness primer cup protection and the groove around the primer cup, French military issue "Balle D" and "Balle N" ammunitions are safe inside a Lebel's tube magazine. However currently available commercial ammunition, such as old Remington 8mm Lebel ammunition or new(Prvi Partizan) 8mm Lebel ammunition, or pointed bullet reloads made with reformed .348 Winchester brass or Prvi Partizan brass, may all create a real risk of accidental firing inside the Lebel rifle's tube magazine. Flat nose 8mm bullets only are a much safer alternative.
The last type of Lebel military issue ammunition to be introduced was the Cartouche Mle 1932N, using a steel and cupro-nickel jacketed spitzer boat-tailed bullet which was only suitable for Lebel and Berthier rifles marked "N" on top of the receiver and barrel. Manufacture of this ammunition, originally designed to increase the range of the Hotchkiss machine gun, ceased in France during the late 1960s.
8mm Lebel ammunition was powerful for its time. It ranked slightly higher in muzzle energy than .303 British and slightly lower than the German 7.92×57mm Mauser cartridge. The chief negative characteristic of 8mm Lebel ammunition was the geometry of its rimmed bottlenecked case. This adversely affected the magazine capacity and functioning of firearms, particularly in automatic weapons such as the Chauchat machine rifle. The Lebel cartridge's heavily-tapered case shape and substantial rim forced weapon designers to resort to magazines with extreme curvatures as for the Chauchat machine rifle. In contrast, rimless straight-wall cartridges such as the .30-06 Springfield and the 8x57mm Mauser could easily be loaded in straight vertical magazines.
Read more about this topic: Lebel Model 1886 Rifle