Moble Supply Units Qaulity

On WG I see that after a while the Weapons on an MSU will make it to 600, but the ammo eventully stops increasing, it keeps using the upgrades but stops improving. In my country West Haven it Stopped increasing at 545, East Haven at 525, Under Haven 504 and 505. My guess is once the Weapons hit 600 the ammo qaulity stops increasing but since it is less than 600 keeps using the Upgrades. This effect is on all of my countries that have Mobile Units, I just listed some examples.

Well it's been three days, no change in Ammo Quality and no reply...

So 14 Days, no shortage of suppies, and they still have not gone up.
And still no reply...