I currently shoot a G5 quest primal 70# 29" draw, but it seems to be just a little too long for me. Is there any way that I can take this down to 28.5" without getting new strings or cams?
I had a bow that had the string twisted down to 25" from 26." Although, I'm not even sure if this is a good practice.
It's a very bad practice. It throws off the cam rotation and decreases the efficiency of the cam. This method can be used for fine tuning of up to +/- 1/4" but I wouldn't use it for adjustments any greater than that. For full 1/2" adjustments the only way to go is either a cam or module change depending on the engineering of the cam.