In France, where experiments were conducted with a 37 millimeter Maxim gun, it was found to be impracticable to use a fulminating cap sufficiently large to ignite the powder and cause it to burn. Therefore, a small ignition charge of black powder was employed, it being put in a capsule or bag and placed next the primer. On firing at the rate of 300 rounds per minute, the black powder, though small in quantity, produced a cloud of smoke through which it was quite impossible to see. The inventor of the gun then prepared for the French some wafers of pyroxyline canvas, which were placed next to the primer, securing thereby prompt ignition without the production of any smoke.
Smokeless powder, made as I have described, cannot be detonated by a fulminating cap of any size or by any means whatever. A large charge of fulminate of mercury placed inside the cartridge case next the primer will not detonate the powder, it serving only to ignite it and cause it to explode. But even this would not cause the powder to explode except it be confined behind a projectile, that sufficient pressure may be run up to make it burn in its own gases.
Some curious experiments with smokeless powder may be tried with a shot gun. If the fulminating cap be large, the powder fine, the wads numerous and hard and the charge of shot heavy, all being well rammed down, and the paper case well spun over the last pasteboard wad, a charge of smokeless powder about equal in weight to one-half of what would be employed of black powder would give about the same results as black powder. But if the charge of shot be omitted, the primer will only ignite the powder, and there will be set up sufficient pressure merely to throw the wads about half way up the barrel of the gun, when the powder will go out. Now if this same charge of powder be collected and reloaded into a new cartridge case and well confined behind wads and a charge of shot, as above explained, it will all burn, giving the same results as black powder.
Attempts have been made to use this powder in pistols and revolvers, but here it has proved a failure, as the pressure is not great enough to cause the powder to be consumed, unless it be in the form of very fine grains or dust, in which case the pressure mounts too high. However, this might be overcome to a degree by making the powder porous. The chemical conditions of the powder might be the same, but the physical conditions must be different. A powder suitable for shot guns and pistols would not be suitable for rifles.
One not familiar with the characteristics of smokeless powder would be almost certain to fail in his first attempt to fire it. Many persons have been convinced by their first experiments that this powder would not burn at all in a gun, any more than so much sand.
Smokeless powder is consumed with a rapidity which accords with the conditions of its confinement. Therefore, the bullets which have been experimented with by different governments have been the cause of much of the varying pressures attributed to the smokeless powders.
The Austrians use the Mannlicher steel jacketed bullet. The steel casing or jacket is first tinned on the inside and then the lead is cast in, thus melting the tin and adhering firmly to the jacket. This projectile sets up enormous friction in the barrel of the gun when used with smokeless powder; as the smokeless powder leaves the gun barrel perfectly clean and the two steel surfaces being in absolute contact cause tremendous friction; and as the coefficient of friction varies with every shot, the pressure in the gun constantly varies greatly.
The German silver covered bullet used by the French has the disadvantage that when firing rapidly the chamber of the barrel becomes nickel plated and great friction is caused, mounting up the pressures and causing the muzzle velocities to fall off.
The Austrians, in order to prevent their steel cased bullets from rusting and to lessen the friction in the barrel of the gun, cover them with a heavy lubricant, which gives the cartridges an unsightly appearance and causes them to gather dust and sand. The French employ a lubricant at the base of the projectile, with a small copper disk between the same and the powder.
Col. A.R. Buffington, commander of the National Armory at Springfield, Mass., has made a steel covered projectile which he prevents from rusting by blackening by a niter process. Several grooves are pressed in the base of the bullet which carry a lubricant, and when the bullet is inserted in the cartridge case the grooves are covered by it. Furthermore, these grooves prevent the lead filling from bursting through the steel casing, leaving the latter in the barrel, as often occurs with the Austrian and French projectiles when using smokeless powder.