I have an question I hope someone can answer, will the current military or in general the body armor being ordered by the Feds stop a .30 cal round or a .44 mag? If not what will they stop?
Try here: http://www.bulletproofme.com/Ballistic_Protection_Levels.shtml
Basically any rifle round will go through IIIA - it’s “soft” armor. If they have the hard plate inserts (III or IV) then shot placement is a little more important.
".30 cal" could be anything from a 30-30 to a .300 Win Mag. There is a world of difference in muzzle energy between the two. Type of bullet and range are also major factors.
We had a guy in our company hit in the back of his flak jacket with an NVA sniper's .30 cal round while he was on Hill 55 in Vietnam. The round hit just above the ceramic plate and pierced most of the ballistic nylon layers. The bullet remained embedded in the ballistic nylon with just the very tip protruding. The tip of the bullet just barely broke his skin, but left a really cool looking purple bruise. I don't remember if he got a "Heart" from this.
The sniper was probably 200-300 meters out and may have been one of the group after Carlo Hathcock, as this occurred about the time Carlos was based on Hill 55.