What exactly do you mean by 'full'?
It's very unlikely that I will write a Gantt-specific print option so you will have to manage with the 'Print Task View' functionality. Basically you just set up the Gantt View to show exactly what you want to print and then print it.
If the whole image is too big to fit on a page (ie. it ends up being too 'zoomed out' to see the detail) you can instead use 'File > Save Task View to Image' and then print it using 'MSPaint' which allows multi-page printing of images,
I hope you understand that print functionality is no longer as essential as it once was now we are increasingly going 'paperless'!