I've struggled with the same problem, and occasionally still do, and for me the reason is too early body turn when I really try to crush it. The disc hitting your left side is a symptom of this; it's not really the disc hitting your left side, but you're hitting the disc with your left side when your arm lags behind and the body is already turning past neutral. You need to delay the shoulder turn past neutral until the disc is at your right pec. When your shoulders are past neutral when you're pulling the disc past your chest, your pull line is toward where your shoulders are pointing - to the right.
At least for me, this is the cause of 90% of my "grip locks".
Nuke, Quasar, Predator, Orion LF, Orion LS, Roc, Comet, VP, Pure