LIFE OF A BIG GUN.

Stratford Evening Post, Volume XXXII, Issue 67, 14 March 1912, Page 6

LIFE OF A BIG GUN.

The “life” of modern high-power guns is short, owing to the terrific energy and excessively, high temperature developed by smokeless powder (says the London Daily Telegraph). The intensely heated ; gases result!ug from the combustion of nitro-glycbrine and .nitro-celhdose powders weaf - 'awhy the interior of the bore, so that after a, comparatively few rounds there is great loss of powder, and the shooting becomes inaccurate, owing to the destruction of the rifling. In our own 12iiu : guns the • effective “life' 1 ’'■ is about 150 rounds with full charges. After that the inner or “A” tube must bo replaced. Of course, most of the practice carried t on> from 'these; costly and short-lived weapons, iupciaca time is done--with half-charges, of which i6i ate calculated*to ho the'equivalent in wear and tear of one full • charge. One peculiar effect of the ■intcnsly hot powder-gas on the steel of which the gun is made is to harden it to a very considerable extent, so that once a gun has been fired it is practically impossible to carry out any mechanical operation in the boro except grinding with an ornery wheel. When the smokeless powder charge in a modern gun is ignited it burns with great fierceness, liberating large volumes of gas at a very high temperature, and producing great pressure in the bore. This intensely heated gas rushes through the bore at immense speed, and washes away the solid steel as a current of water carries away the sand bn the bed of the stream. That the action of the gases is purely mechanical, and Us not due to any melting effect, is shown by the fact that at the end of the powder chamber, whore the temperature is highest, and is continued for the longest period, but is practically no erosion noticeable, where there is no rush of gas, there even after a large number of rounds have been fired. The erosion is greatest in that portion of the bore immediately in front of the powder chamber, through which the whole volumu of the gas pours when the charge is ignited. The rapid destruction of the bore of the gun from this cause is one of the most serious factors in connection with heavy artillery. It renders necessary the provision of a, large reserve of guns to replace those which would be speedily worn out during war. During the conflict with Russia the Japanese were unable to replace some of their guns which had become worn out in this manner, and at the battle of Tsushima Strait the shooting was very erratic. Some of the Russian survivors of the battle described how they watched the big 12in. shells coming towards them, tumbling end over cud in the most extraordinary fashion, and clearly indicating that the rifling of the guns from which they were fired had been completely eroded. Fortunately for the Japanese, the extremely sensitive fuses used by them always caused the shells to explode when they fell, and the Russians sustained heavy losses from these erratic ’’portmanteaus,” as they termed the badly centred projectiles.