400 rounds expended?
What about HITS?
If you put 400 rounds on a windshield, it’s going to DISINTEGRATE from the mass alone. That’s why anecdotal “evidence” is suspicious.
Actually it may not. They don't say what type of vehicle it was. If it had a carbonate windshield or bullet resistant glass, it might not.
What other evidence would you consider? Anecdotal evidence is considered a valid source if there isn't enough quantitative evidence. It's hard to use quantitative evidence because each shootout is different and sometimes the evidence can't be examined after the event. My experience with the 5.56 during Desert Storm was that it wasn't effective at long range or against targets that were hiding behind something as thin as a 3/4 inch piece of plywood.