|Rate of fire||250rpm|
This gun was introduced into service at the end of 1941 as a replacement for the unreliable Sh-37 cannon. It was designed by A.E.Nudel'man and A.A.Suranov with assistance by G.Zhirnykh, V.Nemenov, S.Ludin and M.Bundin.
Other designations found for this weapon were 11-P-37 and OKB-16-37. It was recoil-operated and belt-fed. The NS-37 proved very effective, especially as an anti-tank weapon. With armor-piercing ammunition up to 48mm of armor plates could be penetrated. And in attacks against the less protected rear and upper surfaces this was more than enough even against the well-protected German Tiger and Panther tanks. Against aerial targets the gun was effective also (one good hit was enough to destroy an aircraft), normally the firing ranges used in aerial combat were 400m against fighters and 500-600m against bombers. To break bomber formations, there were also used fragmentation shells with time fuses at ranges of up to 1,200m.
Installations of the NS-37 were made in significant numbers of Il-2 attack aircraft, where two of these guns were carried together with 40 rounds per gun in large underwing gondolas. But there were also a small series of LaGG-3s and some numbers of Yak-9 fighters (variants T, TK, UT) which were equipped with an NS-37 gun (and 20-30 rounds of ammunition) firing through the hollow propeller shaft.
The installation of the NS-37 in single-seat fighters demanded some structural strengthening and redesign of those types. But the problems caused by the large recoil and the great weight of this weapon could never be solved completely. Flight stability during firing of this gun depended on flying speed and length of salvo. The higher the speed and the shorter the salvo, the better was the stability. Normally there were fired no salvos of more than three shots, because longer salvos would inevitably lead to loose of sight and wasting of ammunition.
After the war the NS-37 was replaced by the N-37 of same caliber.