GC-45 howitzer

GC-45 155 mm Howitzer
An ex-Iraqi GHN-45 at the U.S. Army Field Artillery Museum, Ft. Sill, Oklahoma in travel mode
Type	Howitzer
Place of origin	Canada
Service history
Used by	Thailand Iran China Kuwait Israel Iraq Singapore Saudi Arabia
Wars	Iran–Iraq War, Gulf War, Cambodian–Thai border stand-off
Production history
Designer	Gerald Bull
Designed	1970s
Manufacturer	Space Research Corporation, Noricum, NORINCO
Variants	GHN-45, PLL01
Specifications
Caliber	155 mm (6.1 in.)
Carriage	split trail
Elevation	-89 to 1,280 mils
Traverse	Left 534 mils, Right 711 mils
Rate of fire	maximum: 5 rpm sustained: 2 rpm
Muzzle velocity	897 m/s (2,943 ft/sec)
Maximum firing range	39.6 km (24.6 mi) with Base bleed

The GC-45 (Gun, Canada, 45-calibre) is a 155 mm howitzer designed by Gerald Bull's Space Research Corporation (SRC) in the 1970s. Versions were produced by a number of companies during the 1980s, notably in Austria and South Africa.

The most publicized use of the design was in Iraq, where the GHN-45 variant used by some Iraqi artillery units had a longer range than any coalition cannon systems. This initially caused considerable worry on the part of the allied forces in the Persian Gulf War.

The GC-45's general design followed several decades of work by Bull with fin-stabilized artillery shells, starting at the Canadian Armament Research and Development Establishment (CARDE) and later at Project HARP. In these efforts accuracy was not a huge concern, the objective was muzzle velocity, and the test articles were finned darts representing missiles, a low-cost alternative to wind tunnels. Yet with the removal of the rifling and the soft-metal driving band on the shell itself, the shell could be designed purely for ballistics, as opposed to having the external constraint of the driving band. A system combining some sort of rifling for accuracy without a driving band would result in a longer-range weapon. However, such a design was never achieved.

After years of research at his Quebec firing range, Bull eventually settled on a solution. The resulting Extended Range, Full Bore (ERFB) ammunition was key to SRC's designs: a "pointy" looking shell with much lower drag at supersonic speeds. For longer range applications he added a base bleed system (invented in Sweden) that could be screwed onto the standard shell, as well as an even longer-ranged system with a rocket booster.