Yep, been there, done that. Besides the usual shearing off of needle valves, carbs, mufflers, crankshafts, etc. it is less common to see cracked engine housings and sheared cylinders, but certainly doable. I once broke the entire cylinder off the engine (OS .40 I think) and bent the con rod and piston back 60 degrees. It's all in your technique for smacking the ground.