[PzGr40]

Cutaway model of a Russian 100 x 695mm UBM 6 (УБМ 6), GRAU: 3UBM6 (3УБМ6) cartridge as used in the 100mm D-10 gun of the T-55 tank. The BM-8 (БМ 8 ), GRAU: 3BM8 (3БМ8 ) is an APDS-T (Armour Piercing Discarding Sabot – Tracer) anti tank projectile.
In contrast to the “normal” APDS-T cartridges which usually have break away sabots, the sabot of the BM-8 is a one piece sabot that remains complete. The subcaliber projectile is fixated in the sabot by means of four small radial placed pins -at 90 degrees each-, placed half in the subcaliber projectile, half in the sabot. The pins are locked up by little screwed in caps on the outside of the sabot. Upon leaving the barrel, the cup shaped part in the front of the sabot catches the airstream with such force that the four pins shear off and the subcaliber projectile leaves the sabot that loses speed very quick.
The penetrator is a 120 mm lang tungsten carbide bullet with a weight of 2,82 kg. The penetrator is placed in a soft steel body that forms the subcaliber projectile. The soft steel part in front of the tungsten carbide penetrator forms the piercing cap. It prevents the projectile from bouncing off when the target is hit at a low angle. It is held in place by the skin of the subcaliber body that is rolled in over the ogive of the piercing cap. A round aluminium nosepiece is screwed on the flattened top of the piercing cap.The subcaliber projectile weighs 4,13 kg, the complete projectile (with sabot) weighs 5,69 kg. A large tracer capule is screwed in the base of the subcaliber projectile. In flight, the subcaliber projectile has a 55 mm diameter.

At the end of the seventies of the last century the UBM 6 cartridge did not meet up to expectations anymore, and was replaced by the 100mm BM-20 APFSDS-T cartridge.

Vo : 1425 mtr /sec
Penetration : claimed (as far as I can find out) to be 264 mm @ 1000 mtrs.

This is the last posting for this year
Happy ending and a prosporous, healthy and safe 2012

Regards, DJH

[LV]

Thanks again for a great piece. I have the same cartridge as a partial cutaway that was, AFAIK, made for instructional purposes in the Soviet Union. I'll post some photos of it sometime in the future.

You'll probably want to alter the designations in the text a little

100 mm APDS

• Cartridge: UBM 6 (УБМ 6), GRAU: 3UBM6 (3УБМ6)
• Projectile: BM 8 (БМ , GRAU: 3BM8 (3БМ

This may cause some confusion, because of the BM 6 (БМ 6) projectile for the 115 mm U-5TS tank gun.

115 mm APDS

• Cartridge: UBM 5 (УБМ 5), GRAU: 3UBM5 (3УБМ5)
• Projectile: BM 6 (БМ 6), GRAU: 3BM6 (3БМ6)

[PzGr40]

Hi LV, thanks. I've put your added info in my text. Is it correct this way?
Regards, DJH

[LV]

Here's an Excel file with a lot of GRAU designations in both Russian and Czech languages.

[LV]

Hi LV, thanks. I've put your added info in my text. Is it correct this way?
Regards, DJH

Yes, looks good to me. The Soviet/Russian designation system may sometimes be a little confusing. Cheers.

[Nabob]

At the end of the seventies of the last century the UBM 6 cartridge did not meet up to expectations anymore, and was replaced by the 100mm BM-20 APFSDS-T cartridge.

As LV says a little confuzing

UBM 6 cartridge with BM 8 projectile was replaced by UBM 8 cartridge with BM 20 projectile.

Cheers, Bob.

[PzGr40]

Hi Bob,
strange enough the powdercharge in the shellcase was different in the east German drawing I used. It had no sticks in the middle, no liner on the inside of the shellcase and no cartboard spacer. Are there different types?

Maybe X has a quick awnser?

Regards, DJH

[x]

DJ, I wish I had an answer but I do not have the Russian manual for this one. Sad enough...

[LV]

Hi Bob,
strange enough the powdercharge in the shellcase was different in the east German drawing I used. It had no sticks in the middle, no liner on the inside of the shellcase and no cartboard spacer. Are there different types?

Maybe X has a quick awnser?

Regards, DJH

In my UBM 6 cutaway the charge seems to be of the same type as in Nabob's pictures.

UBM 6 of course has a full charge (полный) like the UOF-412 in the attachment. The other attachment shows that there are full charges with different compositions for the 100 mm tank gun. It may be that your East German manual showed just one of them.