>>534391676
They just do that sometimes if it's the one front leg
>>534391113
Here's another two examples:
First, the punisher plasma projectile is only AP2. The fact that you get a ricochet symbol when hitting a cannon tower heatsink means the projectile is making contact, which rules out the sometimes stated belief that the projectile is detonating too early.
Second, bile warriors have 325 main HP and are entirely explosion immune except for the main HP. The punisher plasma explosion only does 150 damage. If the projectile did no damage then these two shots would not be enough to kill the warrior as it should be left on 25 HP. That you can kill them in two direct shots is proof there is additional damage coming from the projectile.

Now, all this being said, getting limb breaks is sometimes inconsistent. It's not because the projectile isn't doing damage, though, it's most likely that the hitbox of the projectile is so large that it is inadvertently clipping other parts of the enemy before it can reach hitboxes that are further in or partially obscured, like the devastator head, or the warrior head when its claws are raised