Well, against a MBT, a 50 bmg would barely scratch it. But these are smaller, remote controlled vehicles, with armor only there to protect the internals and weapons Also, an AR500 can't deal with even the mild steel core .50 BMG rounds.
I wasn't clear on this one and you are completely right mild steel cores will easily defeat reasonably thick plates of AR500 .
However, what I couldn't articulate (sleep deprivation) was that hard steel will cause the jacket break and pieces to spread out after penetration; spalling. Smaller pieces slow down faster in the presence of resistance... cuz Newton. When a bullet spalls it breaks apart and smaller pieces begin to fan out away from the penetration and every little fraction of an inch of space between one plate and another allows the bullet and or fragments to slow down or gives more of a chance to deflect. To a human a penetration would immediately mean game over because meat bleeds. To a robot? nope. Even in the event of a penetration of armor a half assed design would include outer and inner armor layers air gapped, with HDPE or kevlar backing behind the second layer, and the electronics would likely be sealed in their own protective enclosure with the actual components sealed into a block of epoxy. Not counting that there would probably be redundancy built in or that all of the HWPs have domes and curves for armor , meaning deflection and depending on the curvature of the armor and the attack angle would mean that the actual thickness versus the relative thickness HIGHLY favors the HWP.
Let's list this out of the advantages of an HWP armor.
1.Curved outer armor for initial deflection
2.Curved outer armor providing more relative armor against a penetration by its geometry
3.An air gap to catch high velocity spall and encourage deflection between inner and outer armor layers
4.Inner armor probably tilted 5 to 15 degrees relative to center-line to encourage deflection.
5.Spall shielding for inner armor penetration to slow or stop secondary spall
6.Electronic enclosure
7.Epoxy encasement
8.Redundancy
So could a sniper rifle with 50 BMG hurt a HWP? Yes, would it take losts of bullets? yes.
Now with a plasma based weapon... man that is a whole 'nother ball game.
Was that a little more clear?
-HH