User blog comment:Unownshipper/Metallurgists Wanted: Rapture's Natural Resources/@comment-8299550-20140811221953/@comment-75.36.136.107-20140812102744

Well Ryan said (BaS) use aluminum instead of steel. But most times I fired at (non-wood) flat walls it seemed to chip like concrete/stone.

Those windows are another subject - they crack but dont break (except when a Big Sister  happenes to want to drown someone.)

Bulletproof glass? Plastic liner (double paned ...)  Polycarbonate ?