Here is a good link about Yak-9UT
http://mig3.sovietwarplanes.com/yak1...-andermann.htm
"In early 1945, Plant n.166 delivered 282 machines armed with one NS-23 and two syncronised B-20S guns."
So, this means only some prototypes experimented with N-37, NS-45 & NS-57 guns, ALL others indeed had the armament listed above. Also, the game version has indeed totally wrong armament.
The errors in armament found in game (using Il-2 compare) is not limited to this example, here are some:
Yak-3 VK-107 currently has a UB machine gun on the cowling and a ShVAK gun firing throught the prop hub. The real Tbilisi production had two synchronised B-20S guns and one B-20 hub-gun. That is about double the firepower than of the ingame version.
http://mig3.sovietwarplanes.com/yak3...yak3vk107.html
Both versions of MiG-9 should have two NS-23 guns instead of the VYa-23s now modelled. The two weapons were completely different in every respect, in fact the only similarity was the caliber of the barrel. Ammunition (VYa used a larger cartridge case), dimensions and weight (Vya 68 kg vs NS 37 kg), operating mechanism (Vya was gas operated, NS used short recoil) were different. Both had approximately the same firing rate (550-600 rpm) but VYa's muzzle velocity and thus armour penetration was greater (905 vs 690 m/s).
Seems like the NS-23 is not modelled at all, since the other early jet, Yak-15 uses two B-20 guns instead of two NS-23s.
A6M5b is still (since 2004) missing it's 7,7 mm Type 97 machine gun, located next to a 13,2 mm (wrongly modelled as a German MG-131) in the nose.
Also, IJN Type 97s found in other Japanese planes are in fact MG-15s, IJA Type 89s are Browning .303s, and IJN Type 99 cannons (of which two completely different models existed) are all German MG FF guns.
IJN fighters N1K1-J, N1K2-J and both J2Ms use IJA Ho-5 cannons (this would have caused a scandal in WW2 Japan). Also, J2M3 should have the two different types of Type 99 cannon side by side in the wing, with of course had different ballistics.
German weapons seem to have been used in a few other aircraft, including MS.406 and IAR.81.
Even more interestingly (also since 2004), Ki-43 has two Browning .50 cals (!) on the nose, while the Ki-61 has the correct Ho-103s in that position.
Ki-84c has 30 mm guns labelled as "Ho-115", while in real life (if even then) they were Ho-155. The gun seems to be correctly modelled, as it is ridiculously powerful.
The same Sh-37 (as described by WTE_Galway) can be found also on the Ki-46-Kai night fighter.
Last, but not least: the Hungarian built Me 210Ca-1 "Zerstörer" apparently has a 75 mm PaK-40 gun instead of the 40 mm Bofors. Ehhh....
Either Il-2 Compare is complete carbage, or there are indeed many errors and omissions in the game. It would be really awesome if Daidalos Team could do something for this.