A320: The maximum speedbrake deflection in manual flight is:
40° for spoilers 3 and 4
20° for spoiler 2.
The maximum speedbrake deflection with the autopilot engaged is:
25° for spoilers 3 and 4
12.5° for spoilers 2.
A319: The maximum deflection for spoilers is:
25° for spoilers 3 and 4
12.5° for spoilers 2 in configuration 3, and 17.5° in other configuration A321 dont know

. Also the wing loading/load factor would diff for the two a/c. may be the autopilot cannot handle the associated loads of 40dg of spoilers

anyone else care to clarify?