A cartridge or a round is a type of pre-assembled firearm ammunition packaging a projectile, a propellant substance and an ignition device within a metallic, paper or plastic case, made to fit within the barrel chamber of a breechloading gun, for the practical purpose of convenient transportation and handling during shooting. Although in popular usage the term "bullet" is used to refer to a complete cartridge, it is used only to refer to the projectile. Cartridges can be categorized by the type of their primers—a small charge of an impact- or electric-sensitive chemical mixture, located at the center of the case head, inside the rim of the case base, in a sideway projection, shaped like a pin or a lip, or in a small nipple-like bulge at the case base. Military and commercial producers continue to pursue the goal of caseless ammunition; some artillery ammunition uses the same cartridge concept. In other cases, the artillery shell is separate from the propellant charge. A cartridge without a projectile is called a blank.
One, inert is called a dummy. One that failed to ignite and shoot off the projectile is called a dud, one that ignited but failed to sufficiently push the projectile out of the barrel is called a squib; the primary purpose is to be a handy all-in-one for a shot. In modern, automatic weapons, it provides the energy to move the parts of the gun which make it fire repeatedly. Many weapons were designed to make use of a available cartridge, or a new one with new qualities; the cartridge case seals a firing chamber in all directions excepting the bore. A firing pin ignites it; the primer compound deflagrates, it does not detonate. A jet of burning gas from the primer ignites the propellant. Gases from the burning powder expand the case to seal it against the chamber wall; these propellant gases push on the bullet base. In response to this pressure, the bullet will move in the path of least resistance, down the bore of the barrel. After the bullet leaves the barrel, the chamber pressure drops to atmospheric pressure.
The case, elastically expanded by chamber pressure, contracts slightly. This eases removal of the case from the chamber. To manufacture cases for cartridges, a sheet of brass is punched into disks; these disks go through a series of drawing dies. The disks are washed before moving to the next series of dies; the brass needs to be annealed to remove the work-hardening in the material and make the brass malleable again ready for the next series of dies. Manufacturing bullet jackets is similar to making brass cases: there is a series of drawing steps with annealing and washing; the projectile can be made of anything. Lead is a material of choice because of high density, ductility; the propellant was long gunpowder, still in use, but superseded by better compositions, generically called smokeless powder. Early primer was fine gunpowder poured into a pan or tube where it could be ignited by some external source of ignition such as a fuse or a spark. Modern primers are shock sensitive chemicals enclosed in a small capsule, ignited by percussion.
In some instance ignition is electricity-primed, there may be no primer at all in such design. The case is made of brass because it is resistant to corrosion. A brass case head can be work-hardened to withstand the high pressures of cartridges, allow for manipulation via extraction and ejection without tearing the metal; the neck and body portion of a brass case is annealed to make the case ductile enough to allow reforming so that it can be reloaded many times. Steel is used in some plinking ammunition, as well as in some military ammunition. Steel is less expensive than brass. Military forces consider small arms cartridge cases to be disposable, one-time-use devices. However, case weight affects how much ammunition a soldier can carry, so the lighter steel cases do have a military advantage. Conversely, steel is more susceptible to contamination and damage so all such cases are varnished or otherwise sealed against the elements. One downside caused by the increased strength of steel in the neck of these cases is that propellant gas can blow back past the neck and into the chamber.
Constituents of these gases condense on the chamber wall. This solid propellant residue can make extraction of fired cases difficult; this is less of a problem for small arms of the former Warsaw Pact nations, which were designed with much larger chamber tolerances than NATO weapons. Aluminum cased; these are not reloaded as aluminum fatigues during firing and resizing. Some calibers have non-standard primer sizes to discourage reloaders from attempting to reuse these cases. Plastic cases are used in shotgun shells and some manufacturers offer polymer centerfire cartridges. Paper had been used in the earliest cartridges. Critical cartridge specifications include neck size, bullet weight and caliber, maximum pressure, overall length, case body diameter and taper, shoulder design, rim type, etc; every characteristic of a specific
German submarine U-237 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 23 April 1942 at the Friedrich Krupp Germaniawerft yard at Kiel as yard number 667, launched on 17 December and commissioned on 30 January 1943 under the command of Oberleutnant zur See Hubert Nordheimer. After training with the 5th U-boat Flotilla at Kiel, she went to the 23rd flotilla as a trials boat and to the 31st flotilla, she was sunk by American bombs at the Germaniawerft in Kiel during a raid on 14 May 1943, but was raised and returned to service. She was sunk a second time by British bombs at the Deutsche Werke in Kiel on 4 April 1945. German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-237 had a displacement of 769 tonnes when at the 871 tonnes while submerged, she had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower for use while surfaced, two AEG GU 460/8-276 double-acting electric motors producing a total of 750 metric horsepower for use while submerged.
She had two 1.23 m propellers. The boat was capable of operating at depths of up to 230 metres; the submarine had a maximum submerged speed of 7.6 knots. When submerged, the boat could operate for 80 nautical miles at 4 knots. U-237 was fitted with five 53.3 cm torpedo tubes, fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, a 2 cm C/30 anti-aircraft gun. The boat had a complement of between sixty. Helgason, Guðmundur. "The Type VIIC boat U-237". German U-boats of WWII - uboat.net. Retrieved 26 December 2014. Hofmann, Markus. "U 237". Deutsche U-Boote 1935-1945 - u-boot-archiv.de. Retrieved 26 December 2014
The Guébriant Islands are two small islands west of the Antarctic Peninsula, in the northern part of Marguerite Bay, lying 9.3 kilometres southeast of Cape Alexandra, the southeast cape of Adelaide Island. They were discovered by the fourth French Antarctic Expedition 1908–1910 under Jean-Baptiste Charcot and named by him as "Îlots de Guébriant" after the Reverend Jean-Baptiste Marie Budes de Guébriant, a French Catholic missionary to China; the islands were surveyed by the Falklands Islands Dependencies Survey in 1948. They were recharted by a Royal Navy Hydrographic Survey Unit in 1963. Both islands have an elongated shape; the smaller island has a highest point of 92 meters. The southern island is about 1100 m long, it is much lower. The islands are separated by a channel about 200 m wide. In summer they become ice free. About 1 km to the south sest of the islands lies Mission Rock named after missionary de Guébriant. Mission Rock is not considered part of the Guébriant Islands proper. Argentina and the United Kingdom all consider the Guébriant Islands to be part of their national territory, as they fall within the overlapping Antarctic territorial claims of all three nations.
There is however no physical presence of any of these nations on the islands. On a clear day, the Guébriant Islands can be seen from Rothera Research Station, a distance of about 28 km; the flora and fauna of the islands seem to be poorly investigated. An exhaustive publication from 1995 tempting to list all the breeding sites of the snow petrel in Antarctica mentions the Guébriant Islands as a possible breeding site, based on a single observation from 1962; this may indicate not only that the observation from 1962 was sketchy, but that there are no known written records of the islands' bird life in the 33 years thereafter. The vegetation of the Guébriant Islands consists of moss patches of the genera Brachythecium and Drepanocladus, among other things. In these moss communities the most abundant nematodes are from the genera Plectus and Aphenchoides. In moss patches of Drepanocladus these worms may number 428,000 per square meter in just the uppermost 2.5 cm. Alectoria minuscula f. biformis, a species of lichen, was found on the islands by B.
Stonehouse and V. E. Fuchs on 13 October 1948 and was abundant at altitudes above 100 ft. Another lichen species, of the genus Lecanora, was found on the leeward slope of the southern Guébriant island at an altitude of 61 metres in 1961. List of Antarctic and sub-Antarctic islands