Just a follow up on how this worked out for me. I ordered 5/64” ball bearings from Amazon for $8.95 for a hundred. I pressed the ball bearing into the existing, factory, hole in the cap, which takes a tiny bit of force. I used a small arbor press. I think the statement in the 24hourcampfire link that the hole is a #48 drill bit is correct, so my 5/64” ball bearing is just larger than the hole. Maybe I should have drilled out the hole to be a bit larger, but it seemed to work fine and the ball bearing will not fall out on its own.
I have two vx-3 scopes and the holes that are pre-drilled by Leupold are in quite different places relative to the zero mark, which is a bit odd to me, but corresponds to what some other folks have found. Nevertheless, I used these holes because I don’t care if it stops at zero, I just want it to stop somewhere down from zero so that I can easily put the dial back to my zero if it is accidentally turned. I guess if I want it to stop at zero I’ll drill a hole in the appropriate spot in the future. I suppose one advantage of the cap stop being down from zero is if I’m using a new load that is hitting high, I don’t need to loosen the cap to make an adjustment to sight it in (I can loosen the cap to reset it to zero later).
Modified to note that: since the dial has just one turn, you probably don’t want to use the factory hole if it is much below the printed zero on the cap. That would limited your elevation adjustment.
Thanks again for the great info everyone. Once I received the ball beaings it took about 60 seconds to do both caps.