Yep, I think it's called "spaul" (sp?). Some cases. a piece on the inside breaks off, even though the round doesn't penetrate.
Stormin Norman had the right idea. Overwhelming force! On our convoys we used recon-by-fire for any suspected strong points. The bad guys knew what waited them and when they forgot, they soon found out, especially when a few well placed 155mm HE or Willy Pete rounds served for the recon-by-fire weapon of choice. We knew where the likely ambush points were and had the fire direction center work up data. As we approached the convoy commander would call in and they let it rip. Sure took the wind out of them. However, in the kinder and more gentle Army of today that would not be looked on kindly.