Soviet 12.7mm vs Ma Deuce

Was the Soviet 12.7mm ever carried on aircraft? How did it compare to the US 50 calibre?
http://world.guns.ru/machine/mg03-e.htm

[Tony Williams]

The DsHK wasn't - it was produced only as a ground gun, so was comparable with the .50 M2HB (i.e., heavy and slow-firing). For aircraft use the Soviets had the UB (or Berezin for short) which fired the same 12.7x108 ammo. The ammo was slightly more powerful than the .50's 12.7x99 and it generally fired better bullets. The UB was lighter and faster-firing than the aircraft M2, so it was a better all-round package. What I don't know was how reliability compared.
You will find a detailed analysis of the effectiveness of WW2 fighter guns and gun fits on different aircraft on my website (as well as lots of other goodies!).

Tony Williams: Military gun and ammunition website and discussion forum

[Juha]

Hello
IIRC Finns had more reliability problems with war booty Berezins than with US .50s. When Finns tried to use UBs as the central gun of the MS 406 in place of the 20mm "Motor cannon" Hispano UBs suffered for example gun frame/body (not sure which is the right term) breakages.

Juha

[Tony Williams]

Originally Posted by Juha

Hello
When Finns tried to use UBs as the central gun of the MS 406 in place of the 20mm "Motor cannon" Hispano UBs suffered for example gun frame/body (not sure which is the right term) breakages.

That may have been connnected with the installation - was a Browning tried in the same location?

TW

[Juha]

Hello Tony

Yes, it was installed in some MS 406s. I don't know how well it worked, my source, Jukka Raunio's Lentäjän näkökulma II (1993), mentioned only the problems with UBs and mentioned that 12,7 mm Colt was installed in some Ms 406s without commenting how well it worked. (Finns called .50 Brownings as 12,7mm Colts). Also in combat reports from year 1944 there are sometimes mentioned that Berezin malfunctioned during combat, more often pilots just noted that the middle gun malfunctioned, the problem with the central gun of MS were rather common which was critical because the central gun was the only effective weapon in MS late in war, the 2 or 4 7,5mm wing mgs were by then rather ineffective against well protected Soviet a/c.

Nothing definite, I'm afraid. MS 406 isn't my speciality.
Juha

Ps. Fiins also installed Berezins to their Curtiss Hawk 75As (the export versions of P-36) as fuselage gun/guns in place of the 2 light mgs but from 43 onwards they substituted 12,7mm Colts and LKK 42s (Finnish copy of .50 Browning) for Berezins, because latter's unreliability under G-forces, partly because of weak belts.

[Tony Williams]

Thanks, Juha.

That's interesting as the synchronised rate of fire of the UB was supposed to be twice as fast as the M2. The UB's RoF is given as 1,050 rpm free, 800 rpm synchronised, while the M2 managed 800 rpm free and 400-500 synchronised, according to my information.

If only I could gather the information about belts it would make for an interesting study. Nobody pays much attention to them but they were critical to successful performance, and it was important to get the characteristics right; they needed steel of a certain springyness - to use a technical term - which wasn't always easy to acquire, especially under wartime conditions. The 30mm MK 108 in the Me 262 also suffered from belts being pulled apart under G-forces, as did the 20mm MK12 cannon in the Crusader F8U jet fighter.

Tony Williams: Military gun and ammunition website and discussion forum

[Kari Lumppio]

Berezina

Going from memory here, so caveat.

IIRC Berezina problems in the Morane installation were connected with ammunition feed. The Berezin (UB) worked well as Il-2 rear gun. A PoW Il-2 gunner was asked advice and he said to fire only short bursts (5-6 shots, don't remember exactly). Perhaps the rapid fire and resulting high velocity for the ammunition feed plus abrupt stop after shooting were the cause for gun jamming? I do not know if the Berezin-Morane ammunition feed system was copied from some Soviet design or if it was Finnish. If the latter case some ironing out of initial ammunition feed guide problems should be expected.

It looks like by late 1943 some relief was found for the Berezin/Morane problems. At least Berezin was the most numerous center-line weapon in FinnAF Moranes then. Berezin-gunned Moranes seem also got a cooling air scoop over the cowling. Don't know when.


Cheers,
Kari

[Juha]

Hello Kari.

Well, the MS had at least time to time problems with their central gun still in 1944. When vänrikki Eriksson was lost on 25.5.44 all four participating MSs suffered central gun malfuctions. Eriksson (MS- 317)(after returning from Soviet prison camp) and luutnantti Uola (MS-644) reported that their weapons didn't work, kapteeni Turkki (MS-650) reported that the cannon of his a/c (so his a/c seems to have had 20mm Hispano) stopped working after a couple of burst and after a while suffered barrel explosion and vänrikki Kyllönen (MS-637) succeeded get only 2 burst from his middle gun (keskipyssy) before it fell silent and he had only his wing mgs (siipikiväärit) to use. I don't know which if any of the a/c had UB as the central gun, but probably some had. I had copies of some combat reports in which pilots clearly stated that their Berezin stopped firing but usually pilots only mentioned that their central gun malfunctioned without specificing the type. I haven't went through the 1941 -43 combat reports so i cannot say if the situation was worse earlier but it wasn't too good in spring 44. I'm more an operations man and had not checked which MSs had Hispano and which UB as the central gun in 1944.

I put the identifications of the participating MSs in my message, maybe You have the info on which guntype they had as the central gun?
Juha

[Kari Lumppio]

According an undated list from late 1943 all four Moranes (MS-317, -637, -644 and -650) had armament "BS + 2 M.A.C.". This may of course have been changed by May 1944.

Kari

[Juha]

Thanks a lot, Kari.
Gun malfunction rate on that mission was rather catastrofic 100%, even if Kyllönen succeeded to hit one Airacobra badly at the beginning of the fight. Very soon all the Finns were forced to purely defensive fight because the malfunctions.

Thanks again
Juha