Well, there we have it. Your technique sucks.
When you deadlift, do you lock out your legs immediately and then grind the shit up with your back hunched forward? No? Then don't do it with the stones either.
You should try the following: Box front squats with the stone cradled in your hands. For reps.
Pick up a stone you can get easily (like a 110 or 120) and roll it up and down your thighs (don't stand up with it) repeatedly.
Try cradling the stone (hands not facing each other but rather shifted). I lifted the 180 mid-shin without tacky that way. Another advantage is that this technique adds a bit of a spin to the stone so you can roll it up with minimal exertion (loaded a 130 in 3 seconds that way). Then again, that's just my special technique.
Don't blame the tacky. If you couldn't lift it, your technique sucked.
Get stronger on front squats. Most important lift for stones by far.