With at least some sarcasm :tongue3:, unless the water jug...velocity3x wrote:I've watched the video many times...
... spontaneously sprung a leak on both sides violently enough to take a chunk out of the backstop, I think the hypothesis that the core of the projectile might... might... have continued through the brick has some basis..
More seriously, what you're seeing on the video... presumably this...
...is one of the fins of the dart breaking away on impact (as it's designed to do) and does not have the penetrator attached.
I'll give it to you that we're used to water jugs disintegrating with some vigour when hit, but given the penetrator bears a passing resemblance to the ammunition for the APS underwater rifle, penetrating water quietly and efficiently is no great surprise.
The major difference with the second shot was that the penetrator did not hit straight on. It had been bent by its impact with the concrete beneath the target and had deflected sideways into the jug, so the result that time was major cavitation.