Well if you consider that the Hispano is capable of pentrating between 15 and 30mm of armor on the Panzer IV chassy, you'd think that smaller rounds with AP heads would have no problem penetrating the gun shield.
Granted I think a Ostwind crew could haul ten or fifteen strips out of the hull compartment to feed into the hopper, how easy would this be bouncing along at 25 mph?
AAA guns normally only have to fire in bursts because of supporting armor or infantry, but used such as in AH, the barrel would melt fairly quickly

Btw I think only the elevation is porked, while the Panzer IV series had hand cranks for fine adjustment of the gun for the turrent ring, I doubt the Ostwind uses the same gearing system for the AAA gun. Perhaps they even use the electric drive. The Panzer IVJ was the only one to have exclusively hand operated turrent ring, and it suffered greatly in battle because of it. Elevation, however, was hand cranked on the Ostwind by the crew.
- Jig