Also, they need real hardened armor plate, like ar500, not recycled mild steel, if they really want the thing to be bullet proof. Even then, steel core or tungsten core surplus would punch through.

http://www.chapelsteel.com/ar500-ar500f.html

Didn’t Steve Austin work for OSI? There are wheels within wheels.

http://en.wikipedia.org/wiki/Gog_(film)

I’ve looked for clips a few times, but nothing’s ever made it to youtube.

I was so disappointed when I grew up and realized every lab did not have a flamethrower. 

The main drone counter guerrilla weapon would be the Mosin Nagant bolt action and similar .30 caliber bolt action rifles, but also pit traps, deadfalls like when they dropped the railroad carriage on a Terminator,  snares such as cargo and cammo nets, and entanglement traps made of concertina wire which would be completely impassable to a small vehicle.  Fire would also be effective. A meter deep mud pit covered with sawdust and leaves to create a quicksand effect would be very effective because even if the robot escaped it would be covered with muck and it’s sensors would be degraded even if they were undamaged.

Of course the other strategy would be a much smaller and agile bot, something weighing a couple pounds with wheels but the ability to wind a spring and leap.  This could  literally chase people down, and kill them with a  very light weapon like a pepper spray dispenser loaded with sarin gas and maybe a suicide charge.