The hole depth does seem to be a bit variable on the blocks, and with people not clearing the holes, then tapping etc, then over tightening studs can crack the blocks by lifting the threads.
The holes need ideally to be depth measured, and then if necessary the studs trimmed a few mm so that the shoulder of the stud sits in the recess around each hole, all then will be fine, I torque mine to 120lbft, rest 4 hours minimum retorque to 120 again.
tabetha