If you mount an arm horizontally on the back of your robot and use it to sling the balls, would that come into violation of the 30 degree angle rule?
i’m curious as to which rule you are referring. i’ve read the manual several times, and have seen no mention of a minimum/maximum/required launch angle. could you post the specific rule you are referencing?
I think he is referring to this safety rule.
<S02> Muzzle Velocity - No ROBOT may throw a ball with an exit velocity of greater than 12 m/s (26.8 mph).
As a reference, a ball traveling at this velocity when leaving the ROBOT at an angle of 30º from horizontal with no spin will travel approximately 35 feet. A robot that violates this rule will be considered unsafe per <S01>.
This is a SAFETY rule giving a REFERENCE to determine the safe muzzle velocity of the ball. IMHO you can have any angle on the shooter as long as it’s only shoots at 12 m/s.
Hope this helps and I’m right 
the 30 degree rule is a theory that the max a ball can go at 30 degrees at 12m/s /is 30-35 feet. this is a theory on how to judge if a team is launching a ball at 12m/s or faster. seeing as all of the judges having radar guns seem to be a Little over zealous. i believe the only rule that you might want to be aware of is the height violation. hope this helps!