By itself the weapon weighs 72.5 lb/33 kg. It was designed to use the same tripod as the M2 .50-cal. machine gun, but is also found in the turret of the AAV-7/LVTP-7 amphibious tractor. The cyclic rate of fire is from 325 to 375 rounds per minute, but the practical rate of fire is about 40 rounds per minute in short bursts. To achieve the maximum range of 2.2 km/1.37 mi, you have to elevate the weapon to loft the grenades and forget about real accuracy. Practical range for flat-trajectory fire is about 1,500 m/4920 ft. There are several types of ammunition, assembled into disintegrating link belts and transported in metal canisters. The HEDP (high-explosive, dual-purpose) grenade will pierce 2 in./51mm of armor, and spray metal fragments that can kill within 5 m/ 16.4 ft and wound within 15 m/49.2 ft. Other types of ammunition include incendiary, smoke, and tear gas rounds. The Mk 19 is usually found in the weapons platoon of a rifle company and the weapons company of a rifle battalion. One Marine can load and fire the weapon, but it requires a team of three to four to carry it, along with a supply of grenades. It is manufactured by Saco Defense, and the 1994 unit cost was $13,758.00.
Mortars
Mortars are the company or battalion commander's own personal artillery. The mortar is a portable, cheap, and simple weapon: just a metal tube with a bipod elevating bracket and a heavy base plate. You assemble the weapon, aim the mortar at the target, and drop the mortar round down the barrel. The round strikes a firing pin at the bottom of the tube, and off it goes. Limitations of the mortar are its relatively short range and inaccuracy. But this old weapon is now gaining new respect, thanks to the development of precision guided ammunition.
Marines employ two different kinds of mortars. The M224, used in the heavy weapons platoon of the rifle company, is a 60mm weapon weighing only 46.5 lb/21 kg. Maximum range is 2.2 mi/3.5 km. A good crew can sustain a rate of fire of around twenty rounds per minute. The other model, the M252, is used in the heavy weapons company of the infantry battalion. An 81mm weapon, it is based on a 1970s British design, weighs 89 lb/40 kg, and has a maximum range of 3.5 mi/5.6 km. The sustained rate of fire is sixteen rounds per minute. There is a wide variety of ammunition types in each caliber, including high-explosive, smoke, and incendiary rounds. High-explosive rounds can be fitted either with an impact fuse or a proximity fuse that detonates at a preset altitude, showering the target with fragments.
M198 155mm Towed Howitzer
This big gun is one of the more controversial weapons in the Marine arsenal. While it is the Marines' primary field artillery piece, the Corps leadership feels that the M 198 is simply too big and too heavy. Also, it takes up too much space on amphibious lift ships, and in firing position it is too vulnerable, especially when a quantity of ammunition is stacked near the gun. In addition, the M198 has a high center of gravity, which makes it prone to tipping over and being difficult to handle. On the other hand, it uses standard, widely available 155mm ammunition with terrific lethality. Weighing 15,758 1b/7,154 kg, it requires a heavy (5-ton) truck to tow it, along with its eleven-man crew and a supply of ammunition. It can be lifted as a sling load by the CH-53E helicopter. The M198 can hurl a projectile up to 14 mi/22.4 km, and a special rocket-assisted projectile extends this range to 18.6 mi/30 km. The 566 guns in the Marine inventory will serve for at least another decade, until the introduction of a new lightweight howitzer which is under development.
Mk 45 5-in./54 Naval Gun Mount
With the retirement of the Iowa-class (BB-61) battleships, the Navy's gunfire support capability is reduced to one or two of these rifled 5-in./ 127mm weapons on each major surface combatant (cruiser, destroyer, and a few amphibious ships). Built by United Defense's Great Northern Division, the Mk 45 5-in./54 turret has a high degree of automation, sustaining a rate of seventeen rounds per minute. The turret normally operates unmanned, with the six-man Navy crew working below decks. The Mk 45 can throw a 70-1b/31.75-kg projectile to a maximum range of 14 mi/23.6 km, though extended-range ammunition is under development. The main ammunition types are high-explosive and incendiary (white phosphorus). A ship generally carries several hundred rounds per gun in its magazines, and major task forces are accompanied by ammunition ships, which can rapidly replenish the supply, using a UH-46 helicopter.
The Future: The Lightweight Howitzer and Arsenal Ship
Solving the problem of replacing the fire-support assets lost since Desert Storm is a joint Navy/Marine Corps challenge. The most urgent fire-support upgrade is replacement of the M198 155mm howitzer. Six different industrial teams have produced competing designs for a new lightweight howitzer. These include United Defense, Lockheed Martin, Royal Ordnance, and VSEL. In addition to lighter weight, the Marines want a weapon with much longer range (which means a longer barrel) and smaller crew requirements, and a higher rate of fire (which means power-assisted ramming and loading.) Expect to see deliveries in the early years of the next century.
A bigger problem is offshore fire support. Marines really miss those old Iowa-class (BB-61) battleships. Nothing will ever match the spectacular effect of 16-in./406mm shells falling on a target within 25 mi/40 km of a coastline. Over a hundred ships with 5-in./ 127mm guns have left U.S. Navy service, gutting naval gunfire capability. To make up for this drawdown, the Chief of Navel Operations and former Deputy Chief of the Joint Chiefs of Staff Admiral Bill Owens conceived the idea of the Arsenal Ship. The Arsenal Ship would replace the lost firepower of the retired Iowa-class (BB-61) battleships by constructing a simple, relatively inexpensive ship packed with missile launch cells — as many as 732 tactical missiles, including Tomahawk and perhaps a version of the Army TACMS. In effect, the arsenal ship would win the war in one salvo, and then reload for the next war. The ship would rely entirely on off-board sensors for targeting. Covered with radar-absorbing coatings, an Arsenal Ship would have virtually no superstructure. Some design studies envision ballast tanks that could be flooded to give the ship extremely low freeboard, making it a very difficult target for enemy anti-ship missiles. Unfortunately, all this thinking hasn't gone very far; and there are practical problems. Not the least of these: The Navy has done virtually nothing to integrate and procure the TACMS missile for naval service, perhaps because it's reluctant to use an Army missile aboard Navy ships (the "not-invented-here" syndrome). Only nuclear submariners have done substantive work on TACMS, since they are desperately looking for new missions for their subs in the post-Cold War period. Whatever happens, supporting fires will be the make-or-break item for continued forced-entry capabilities into the 21st century.