Yeah that's why you want to puck it into a solid piece of hash first before trying to really juice it. I usually try and squeeze it a bit once its in the bag to suck up extra room where it could quickly expand. There's a Pure Pressure video where they apply a bit of pressure, then release completely, and then ease back into it. Blow outs with hash definitely suck, if you can get a nice little brick going it should be a bit easier to juice in my experience.