I thought so too. And I did some tests. Despite the fact that I selected all the particles for drilling, the AUTOMATIC contact worked with penetration into the rigid body, and the ERODED contact worked without penetration, but the solution time was 12 times longer. I use 48 cores to solve a problem. I'll show you the screenshots.
I used the material Mor-Columb sandstone, I increased the density like that of LSTC:
Calculation using AUTOMATIC contact:
Calculation using ERODED contact:
By the way, the voltages are very small. This is fine?
Then I reduced the density to the one required for the selected system of units, the calculation time increased many times, but for me it is doable. A rigid drill squeezes particles out of the ring, drilling does not occur:
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