GC-45 howitzer

The GC-45 (Gun, Canada, 45-calibre) is a 155 mm howitzer designed by Gerald Bull's Space Research Corporation in the 1970s. The GC-45 combines a number of features to produce what is generally considered the best field piece in the world. The Iraqi version, known as the GHN-45, was cause for considerably worry on the part of the allied forces in the First Gulf War and required almost the entirety of the US Marines air forces to be dedicated to wiping them out.

The general design follows several decades of work by Bull with fin-stabilized artillery shells, starting at CADRE and later at Project HARP. In these projects accuracy was not a huge concern, muzzle velocity was, and the test articles were finned darts representing missiles. 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 being located near the balance point of the shell. A system combining some sort of rifling for accuracy without a driving band would result in a much longer ranged weapon.

After years of research, Bull eventually settled on a solution. Instead of conventional rifling where the shell rides on raised "lands", his design effectively used "reversed rifling", grooves cut into the barrel. The shell rode the rifling via small "fins", and had no soft-metal area where the propellant could "blow by" the shell, allowing much more powerful propellants to be used. The resulting Extended Range, Full Bore (ERFB) ammunition was key to SRC's designs, a "pointy" looking shell that carried more explosive than conventional designs, had much lower drag at supersonic speeds, and was more accurate. For longer range applications he added a base bleed system, as well as an even longer-ranged system with a rocket booster.

Now all that was needed was the weapon to fire it. Using the US-standard 155 mm (6 inch) M109 howitzer as the basis of his experiments, the GC-45 was developed boring out the barrel to a smoothbore, cutting the new rifling into it, and welding an extender onto the end. The result was a 45-caliber weapon in place of the original 39-caliber M109, and when used with "zone 11" propellants (as opposed to "zone 7" for the M109) could place the base-bleed rounds at 39,000 m with the same accuracy as the M109 at its maximum range of 18,200 m. At shorter ranges the GC-45 could easily repeatedly place rounds into 10 m circles, and could be used in the direct fire role to about 3,000 m. A new mounting was designed that was able to handle the increased recoil, on a four-wheel chassis and a small Diesel engine acting as an APU, driving hydraulics that could set up the gun in two minutes, and move it short distances.

Bull worked with NORICUM in Austria to produce a new-build version of the GC-45. The first foreign sales were 18 GC-45s with ammunition, which were sold to the Royal Thai Navy for use by their Marine Corps. NORICUM later modifed the design for easier mass production as the GHN-45.

Iraq was the biggest customer, and their GHN-45's dominated the battlefields during the Iran-Iraq War with their range. During the Gulf War, however, the GHN-45s proved less effective then anticipated by either side. Air strikes had disrupted the Iraqi command and control facilities, and because most of their gun tractors had been withdrawn to serve with logistics units in a attempt to re-supply the front line troops, they were unable to withdraw when under fire. Thus the majority of the guns were destroyed in their positions either by air strikes or Multiple Launch Rocket Systems (MLRS) counter-battery fire.

The GC-45 design was financed by South Africa during the santions period. The G5 howitzer (developed from the GC-45) was intergrated into the South African Army in 1982. These saw service against Cuban and FREMELO forces in the Angolan conflict, where they soon wiped out FREMELO artillery in the border areas. With highly accurate artillery pouring down far behind the front lines, any offensive actions were impossible, and led directly to the ending of active hostilities. Some G-5s found their way to Israel where they were used to good effect in the Bekka Valley in 1986. The G-5 gun has been placed on an Alvis 6x6 chassis as the G6 howitzer, and won major export sales to the United Arab Emirates and Oman. It is also fitted into a turret that can fit on any suitable vehicle. The turret is marketed as the T6 which has already being fitted on the T-72 and a 4 x 4 wheeled truck.

The Chinese armed forces also used the NORICUM version, producing it as the Type 89 starting in [[1986]. They also mounted it on a locally-designed tracked chassis to produce the PLZ-45 (also known as the Type 88), along with a ammo-carrier based on the same chassis. Interestingly the PLZ-45 did not enter service with the PLA due to costs, primarily because their existing artillery was all based on Soviet-standard 152 mm ammunition. However two major batches of PLZ-45's were sold to the Kuwaiti Army in 1997 and 2001.

The dominant artillery system in the "western world" remains the US 155/39 as used in the M109. When it was first introduced the ERFB concept was rejected for NATO service, but a slower post-Cold War upgrade series led to it being re-evaluated when new puchases started in the mid to late 1990s. An even longer 52-calibre version of the basic GC-45 system appears to be becoming a de facto standard for these newer designs. With ranges of up to 47,500 m, Bull's basic design now dominates all future artillery systems.