Many problems were revealed when the P-26's operation began. Due to its narrow landing gear tread and a landing speed too fast for its time, the aircraft was prone to nose over. When this happened, the pilots were often killed, although the planes themselves were not seriously damaged. As a result, the fuselage spine fairing was redesigned. Its height was increased by 20 cm, and the reinforced structure could endure a load of more than 12 tons if hit. The 29th production P-26А was the first to obtain this enlarged fuselage spine fairing, and the planes already produced were modified directly on the front lines.
New wing flaps allowed the aircraft's landing speed to be reduced. The plane was also equipped, in the event of an emergency landing on water, with two inflatable sacks occupying the containers in the wing roots. Beginning at the 26th production aircraft, this equipment became standard for the P-26А, but it was not installed on the aircraft already produced. There is no documented evidence that this system was ever used for its intended purpose, but one aircraft crashed after the raft kit opened spontaneously during flight.
P-26Аs produced later had reinforced armament: one synchronous 7.62 mm Browning M1 machine gun to the left of the fuselage and one synchronous large-calibre 12.7 mm Browning M2.5 machine gun to the right. The magazine capacity of the large-calibre machine gun was 200 rounds.
A combined total of 111 machines of the P-26A variant were produced. The 20th Fighter Group was the first in the USAAC to be armed with Peashooters. It was followed by two more: the 1st Fighter Group based in Selfridge, Michigan, and the 17th Fighter Group at March Air Force Base, California. At various times, P-26s were operated in 22 USAAC fighter squadrons.
Peashooters were flown by many pilots who later occupied high positions in the USAAF and then in the USAF, including Henry Harley "Hap" Arnold, future Commander-in-Chief of the USAF.