1. Get two people
2. One person stands in front of the bush then backs up into it (to make sure you just aren't missing)
3. The shooter should fire when he can't see the other tester.
4. With 5.56 and 6.5 rounds little to no damage will be done by nearly all rounds, though 6.5 is somewhat more effective. 7.62 is even more effective, but headshots at close range (both players inside the bush, able to see each other) can still do nothing. The 9mm SMGs will do no damage even when both players are inside the bush only inches away from each other. Vehicles mounted with HE autocannons will notice that it is impossible to kill someone in these bushes, thrown and launched grenades have a similar (lack of) effect.

It makes sense that these bamboo clusters should have some effect on the rounds passing through them, but currently it is nearly impossible to kill a player inside of one. It's as if the bamboo forms an impenetrable shield around anyone inside it, even to the point of two players in the same bush being unable to kill one another.