The 127mm Heavy Gun M144 is the larger counterpart to the 105mm Gun M140, which has been replaced in Army and Marine Corps service by the armored M65 Asssault Gun, or "105mm Gun Motor Carriage, Tracked, M65". The M144 itself was developed from the standard American 5"/54 Mark 42 dual-purpose naval gun, and is capable of crippling any Armored Fighting Vehicle at extreme ranges. Only the 155mm cannon of the M70 Tank Destroyer is more powerful.
The M144 is an extremely large, heavy piece of artillery, and boasts a 64-calibres long barrel. Early production versions (pictured above) had an L/54 barrel, the same as the Mark 42 naval gun, a pepper-pot muzzle brake and a different carriage. The modern M144A3 model has a longer barrel, better gunshield, stronger recoil mechanism and an eight-wheel carriage, but retains the somewhat dated pepper-pot muzzle-brake design. The back two pairs of wheels are detatchable from the rest of the system, while the front pairs are lifted up in order to lower the gun to the ground and deploy recoil-absorbing armatures from the sides. Setting up this massive weapon - which weighs some 7 Metric Tonnes - to fire is a time consuming process. However, once in place, the gun's extreme long distance accuracy and power makes even a single M144 a deadly threat to attacking tank formations.
127mm Gun Motor Carriage, Tracked, M145Edit
The M145 is a thorough update to the existing upgraded M144A3 weapon system which is being retroactively issued to existing anti-tank artillery units. The M145 is a self-propelled version of the M144A3 L/64 gun mounted on an updated M48 Pershing tank chassis. This chassis is elonagated, with an extra road wheel / return roller for the lengthened tracks, and boasts some retrofitted upgrades - the more reliable and effective Continental AVDS-1790-2 V-12 engine used by the M60 Pershing and M65 Assault Gun, lighter weight aluminum road wheels and a front glacis plate addition that grants limited ability to resist Russian RPG rounds.
The M145 system has been issued to most M144 Anti-tank Gun equipped units and has several advantages. It is a self-propelled system capable of towing its own ammunition, requires much less set-up time and has limited protection against most types of weapons fire (except at very short ranges). The M145 protects the crew with a thick, open-topped and open-backed casement and has a frontal .50-cal machine gun position, manned by the radio operator as on the M65, to provide limited anti-infantry support. However, the M145 is an artillery piece, not an assault gun, and is operated by Artillery Crews just like the M144 towed gun described above, with the addition of a two-man vehicle crew consisting of a driver and radio operator in addition to the gun team.