BULLET RESISTANT GLASS FOR .50 CAL PISTOLS As for those ever-more-common .50 caliber hand-canons, Jim has good news: Although not rated for this use, it’s likely that conventional Level 4 bullet resistant glass would stop a standard or Magnum .50 cal bullet. A .50 caliber pistol throws a 325 grain bullet at 1,500 foot-pounds to a speed of 1,400 feet per second. By way of comparison, a .44 Mag bullet is 240 grains (a bit lighter), with 1,000 foot-pounds of energy (a bit less force), getting up just past 1,400 feet per second–and that can be stopped by a Level 3 system. Move up to Level 4, and you can stop a .30-06 hunting rifle bullet (the little cousin to the .50 caliber military round); this is a 180 grain bullet (clearly much lighter than the .50 cal pistol round) with 3,000 foot-pounds of energy (twice as much as the .50 cal pistol) moving at almost 2,800 feet per second (again, nearly twice as fast as the .50 caliber Magnum bullet).