The way some guys handle green sand is just asking for scrap castings.
I keep seeing people ram the sand into the flask without any real care for uniform density, especially in the corners. That's a direct ticket to a blow or a buckle, and I've pulled enough bad pours from the shakeout to prove it. What's your method for packing a consistent mold?
Ramming it in is the main mistake. You need to press the sand down in layers and really work it into the corners with your fingers first. A consistent mold comes from steady pressure, not just filling the flask.
Honestly, people just ram it in? That's wild. I've seen guys wreck a whole flask by doing that, and then they act surprised when the casting's junk. You gotta take your time and work it in layers.