VIDEO: Weapon Penetration Effects

Sent in by a reader, an interesting video for the USMC showing various weapon penetration effects. 
It’s a good video, but I noticed a couple of oddities:
When you watch it, it would appear that the AK, firing 7.62 x 39mm rounds, is very effective at all angles against the structure. When you get on to the M240, which fires the 7.62 x 51 rounds (i.e. .308) it almost appears less effective, with not all rounds passing through the cinder block at a 45 degree angle. Personally, I’m not convinced by that part i.e that the AK is shown as more effective than an M240.
The M16 and the SAW are both firing the same 5.56mm ammo. I’m not sure what ammo they used for these tests, but if you walk my ranges and see the trees, where people are firing a mixture of 55 grain 5.56 and 62 grain 5.56 M855 green tip, you will see multiple trees where, (guesstimate) anything up to at least 8 inches wide has rounds passing right through the tree trunks. 
Also note the effect of the grenade, and how the fragments tear through the walls of the room. 
Food for thought, and comment. I have mentioned in my writings how rounds will just tear through structures, and you have to be  careful over what is cover, and what is concealment only. For those who want to defend from inside your house, think about this stuff ripping through. 
Let’s not start a 5.56 bashing debate hey…..
Live Hard, Die Free.