Mostly only Russian tanks or other non-western countries use 125mm, for example the T-72,T-90 or Type 98, while all (or almost all) western tanks use
120mm or less, including the M1A2 Abrams and Challenger 2.
Originally posted by rogue1
The Soviets fielded a laser guided round for their 125mm smoothbore guns. I think it was called the AT-8 "Cobra" by NATO. It was supposed to be effective out to 8km.
Krasnovia completes fielding of the T-80 tank. The T-80 provides the OPFOR with a distinct advantage over the T-72 with its AT-8/SONGSTER antitank guided missile. The missile has a MILES range of 4000 meters. Its effectiveness is becoming a significant factor on the NTC battlefield. Refer to the Threat Update on page 15 for more information on actual T-80 capabilities.
The AT-8 (Songster) is a Russian ATGM. It was designed to be fired from the 125 mm smooth-bore gun. It uses radio for guidance from the gunner. The AT-8 has a flight speed of 250m/s and a range of 4000m. It can penetrate 550 mm of flat steel and 445 mm of sloped steel armour.