convolutional code

All,
    i build two simulink models to watch the benifit of convolutional
code.
    The first one is: Burnoulli bits ----- 16QAM ------ modulation ----
AWGN ----- demodulation. The parameter of 16QAM modulation module is:
'normalizztion method'= average power and 'average power'=1 watt. The
parameter of the AWGN channel module is 'Eb/N0'=14.55 and 'input signal
power'=1 watt.
The BER is about 1E-6.
    Convolutional code and decode module is added to the second model. The
same BER (1E-6) is achieved with Eb/N0=14.25.
    So, The CC only gives 0.3dB coding gain! Is that value correct? Or
something with my simulation?