Issue with angle limiting - c++

Question

I am creating a game using SFML 2.2 and Box2D. The game is similar to Peggle in that you have a cannon attached to the top of the screen. I have the movement of the cannon mostly working but I would like to limit the rotation so it cannot rotate and point straight up (off screen). I have implemented the code below and it works to an extent. The cannon can move fine within the bounds, but if it hits one of the two edges it becomes stuck there. If I press the opposite direction, instead of rotating back around it quickly jumps to the opposite edge, causing the cannon to be either all the way to the right or all the way to the left.
In my game, when the cannon is pointing straight down the angle is 0/360 degrees, all the way left is 90 degrees and all the way right is 270 degrees.
//******************************/
// Aiming Controls
//******************************/
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Key::Left))
{
float sin = sinf(-m_fRotationSpeed*elapsedTime);
float cos = cosf(-m_fRotationSpeed*elapsedTime);
sf::Vector2f newDirection;
newDirection.x = (cos*m_vAimDirection.x) - (sin * m_vAimDirection.y);
newDirection.y = (sin*m_vAimDirection.x) + (cos*m_vAimDirection.y);
//Update sprite rotation
// Find angle of rotation by acos(v1dotv2)
float rotationAngle = acosf(1 * m_vAimDirection.y);
// Check to make sure we get the right direction!
if (m_vAimDirection.x < 0)
rotationAngle = (b2_pi*2.0f) - rotationAngle;
// convert to degrees
rotationAngle *= 180.0f / b2_pi;
// HERE IS WHERE I CHECK THE BOUNDS
if (rotationAngle > 88.0f && rotationAngle < 272.0f)
rotationAngle = 88.0f;
else
m_vAimDirection = newDirection;
//apply new rotation
m_sCannon.setRotation(rotationAngle);
}
else if (sf::Keyboard::isKeyPressed(sf::Keyboard::Key::Right))
{
float sin = sinf(m_fRotationSpeed*elapsedTime);
float cos = cosf(m_fRotationSpeed*elapsedTime);
sf::Vector2f newDirection;
newDirection.x = (cos*m_vAimDirection.x) - (sin * m_vAimDirection.y);
newDirection.y = (sin*m_vAimDirection.x) + (cos*m_vAimDirection.y);
//Update sprite rotation
// Find angle of rotation by acos(v1dotv2)
float rotationAngle = acosf(1 * m_vAimDirection.y);
// Check to make sure we get the right direction!
if (m_vAimDirection.x < 0)
rotationAngle = (b2_pi*2.0f) - rotationAngle;
// convert to degrees
rotationAngle *= 180.0f / b2_pi;
// HERE IS WHERE I CHECK THE BOUNDS
if (rotationAngle < 272.0f && rotationAngle > 88.0f)
rotationAngle = 272.0f;
else
m_vAimDirection = newDirection;
//apply new rotation
m_sCannon.setRotation(rotationAngle);
}