How much soft armor does it take to stop a rifle round?

[chopinbloc]

Can a .300 AAC 147 gr FMJ at about 1,900 fps be stopped by one level IIIA panel, one level IIA panel, and two IBA groin protector panels? For reference, this velocity is roughly equivalent to M80 7.62x51mm at about 400 yards so another way of looking at it is whether any reasonable amount of soft armor can stop rifle ammo at long range.

 

[strambo]

I'll say "sure" before watching the video. Pretty sure military soft armor (groin pro) is IIIA as well.