Original sentence: The BMP-1 main gun is unable to penetrate the front armor of modern NATO MBTs such as the US M1A1 Abrams, the British Challenger 2 or the German Leopard 2 but it has been claimed that it can penetrate the side armor of these tanks in some areas
Edited sentence: This gun is unable to penetrate the front armor of modern NATO MBTs such as the US M1A1 Abrams, the British Challenger 2, or the German Leopard 2, but it has been claimed that it can penetrate the side armor of these tanks in some areas