I get asked a lot , will NIJ Level 3 ( UL Level 5 ) Ballistic Glass stop the Green tip M855 (5.56) round. My answer is Yes , but let me explain how I arrived at that answer. In the field I`ve never seen this round penetrate this level of glass glad poly carbonate. With that said , I`ve seen the M855 bounce off Mil. Spec. 46-A- 100 (.250) hardened steel plate shot from a 1in9 16" barrel , only to see it penetrated with XM 193 (ball) ammo shot from a 1in7 20" barrel . When we chanced the M-16 (AR15) rifle to the modern shorter version of the M-4 rifle we lost a lot of what Eugene Stoner had in mind for this round. When I first started working will ballistic composites I developed a Phenolic Kevlar / Polyethylene hybrid that stopped the green tips cold " in the field " , but when I sent it out for independent testing all 3 shots of a 3 on 3 special threats test when through the test sample the witness plate and as far as I know they are still headed south. I could not understand what the disconnect was because the key hole effect on the face of the samples was apparent . I was later schooled by a friend " Who has forgotten more about ballistic fiber than I will ever know" . He explained that all samples tested at the lab were shot a zero obliquity from a bench mounted rifle at max speeds . It`s the worst case scenario , not something you would ever see in the field. He went on to explain my success in the field was a result of a plus or minus 5 to 10 degree variation of the strike face from zero and level. This difference is what makes sloping armor so much more effective. For my money , the chances of taking a level, zero, on center view port shot in the field are about the same as winning the lottery. "But I think we will independently test it later this season just to be sure".