Shots rang out throughout the Tunnel with gunfire and explosions as the squad lay down everything they've got on the charging bus-sized bug, the shotgun's explosion itself did very little to the weakened but still flexible carapace plates, it's explosion not quite explosive enough.
But the MAG fire smashes into it, cracking many plates in many spots on it's softened underside, making spiderweb-like cracks anywhere the metal slug smashes into it at breathtaking speed.
And then came the Rod. Supercharged Large metallic penetrator fired with the force of a minor god with a not-so-minor anger using enough power to fuel a small banana republic for a whole week, and was already travelling at a significant fraction of the speed of light by the time it had exited the barrel. The Atmosphere could not explode fast enough and the following shockwave were enough to crack the ground closest to the firing, corpses and bug goo were blown right off of the squad as their state-of-the-art Space Gyro-stabilizers struggled to hold you still against the very force of nature itself.
Then the Rod hit. It penetrated the Bug through it's weakened, cracked carapace as if it weren't even there, the following shockwave were some of the most interesting thing the scientists back at home will be watching at Super slow-motion through Ricardo's camera as it expands the entry wound into incredible size.
But to everyone else, the Bug was charging, then there was an explosion followed by a series of gunfire and smaller explosions, then the whine of their suit's Gyro-Stabilizers working on overdrive anchoring you to the ground, followed by several Sonic booms happening at the same time and then you realize that the bug had been blown apart right down the middle, it's two halves on the floor still twitching, it's legs still trying to run but finding no purchase as if it hadn't even realized that it's dead already yet.