Nope, but my grandpa was a WWII POW and then went on to work in my country's national airline. So the house is kind of filled with aircraft memorabilia and models. You can say that I caught the military virus quite early in my youth. Never enlisted, though - body was never tough enough for that.
Ah, well, the term "MIRV" is used when the smaller warheads detach in space and then reenter the atmosphere to strike their target (and usually those are nuclear weapons, not HE heads)...and as far as I know there are no tactical antiship missiles that use this concept - they prefer the unitary, penetrative warhead to the multiple warhead concept. Much less expensive and probably more efficient since it guarantees at least ONE big hole in the target's hull - your "MIRV"-like idea would create a "trauma" effect all over the ship but it remains to be seen whether they can bring down the ship instead of just dealing massive, extensive damage (it should be noted that in the Falklands war, the HMS Sheffield was sunk by an Argentinian Exocet missile, but its warhead failed to detonate...however, the fuel it still contained caught fire after impact and spelled the ship's slow and painful doom). However, antiship missiles have proximity fuses and can self-detonate in the target's direct vicinity - causing the supersonic debris to intentionally act as shrapnel - which is the next best thing to your idea.
Well, as far as I know, the FAL and its inability to fire full-auto with an acceptable heavy caliber and preserve accuracy was one of the main reasons why people created the .223 caliber (which was even smaller than the British's alternative design, to the point that they threatened to never adopt the American .223). But the FAL was certainly powerful and good enough to be used as a "freedom rifle" all around the world (especially in Africa), right next to the Kalashnikov and be awarded several production licenses. It just can't be used the same way people handle an AK47 or an AR15.
On a separate note, I don't see why some shooters nowadays want to use full-auto with 7.62 rifles, unless it's for kicks (pun intended), it's a actually lightweight machine gun, it has a particularly well-performing recoil mitigator system or boasts a low rate of fire (thus reducing the loss of control, like on the M60). It's a grievous waste of money IMHO and nowadays, all soldiers learn how to save ammo instead of spraying it all around.