Some weapons and armour questions - WINSPMBT v 4.0

[Psiaczek]

Hi, I have some questions:

1)M60 Patton MBT - in most OOBs it has armour front hull:26, front turret: 26. But in some countries OOB, if I remember correctly : Austria, Yemen, and two others I forgot, M60 is front turret:23, front hull: 25 . Are those tanks weaker export wersion or is it mistake in data?

2)30mm 2A42 gun in Russia OOB has accuracy 24, and in most other countries I checked (armies of former Warsaw Pact: Poland, Bulgaria etc.) 2A42 gun has accuracy 19. Are those guns weaker export versions or is it mistake?

3)Russian tracked APC BTR-80A in Russia OOB is available from 1997 if I remember correctly, and I have book which claims BTR-80A fighting in Chechenia 1995? Moreover, in Russia OOB BTR-80A has GSH-30 cannon, and in some other OOB it has 2A72 30mm gun.
Why?
No empty slot in Russia OOB for 30mm 2A72 gun or something else?