The US Optics EREK turret lets you zero, then hold the erector in the zeroed position with a hex wrench in the center screw socket while you rotate the turret clockwise until its bottomed out.
Use the included zeroing turret cap, which has a hole in the center to allow access to the center screw, to zero. Once your zeroed and the turret is all set up for zero stop, swap the solid cap back on.
So, it lets the bottomed out position of the knob itself act as the zero stop.
I like to set my EREK turret to bottom out .5 mils below my zero. That makes it easy, without looking, to spin the turret to the stop then count .5 mils back to zero. It also lets me dial .3 down and .3 right for my unsuppressed zero.
I use the ST-10 TPAL too.