When the P-40D and E went into service, several problems were discovered. When maneuvering in high G turns the guns would often jam due to the way the ammunition was stored. Another problem was that engine and trim management were both somewhat complex and taxing with earlier P-40's required strong rudder pressure to offset engine torque and frequent trim adjustments were needed during rapid speed changes. Both these problems were remedied sometime late in production by enlarging the vertical stabilizer and changing how the ammunition was stored.