IOW, you're saying a Vulcan cannon or Metalstorm can't harm the LeShay based on the stats of a completely different weapon. That makes no sense.
There is- quite literally- a huge difference in the size & mass of the projectile launched by a minigun and a Vulcan. That is why it is used to destroy tanks.
http://www.rense.com/general93/mime-attachment 96.jpeg
In the 6 second round the Metalstorm was trained on a LeShay, that would mean 100,000 rounds of ammunition potentially hitting it- approximately 1000x the number of rounds delivered by the minigun. There simply is no weapon statted out in D20 that approximates this.
Metal Storm 36 Barrel Prototype-One Million Rounds per Minute Rate of Fire - YouTube
And the fact that something from the RW isn't statted out shouldn't remove it from consideration in what is, essentially, a thought experiment.
It is a thought experiment, one I am finding quite entertaining, but the only common frame of reference we have here is the official stats.
You seem to think that automatic weapons can do 800+ points of damage in one round. I reject that concept on the grounds there is nothing anywhere in the rules to suggest that any automatic weapon can do even close to a high three-digit damage total.
Yes, Metalstorm throws an incredible number of rounds in a ridiculously small amount of time. I'm quite familiar with the weapon system, I am also aware that a number of practical considerations have kept it in the prototype phase for years now and it's not an operational weapon with any army because the serious issues in making it operational. I'm also familiar with the well established precedent in d20 Modern/Future rules that automatic weapons don't scale linearly as the number of rounds fired increased.
As I noted, Hastur from Call of Cthuhlu has less staying power in a fight than a LeShay. The same attack that could kill a LeShay in one hit or one round could also take down Boccob, Lolth, Vecna, Wee Jas, Aphrodite, Hercules, Hestia, Anubis, Imhotep and Sobek. (looking in Deities and Demigods). Realize that's the scale of damage you are talking about here.
I pointed out that this is enough to take out armored vehicles and all within, then extrapolated from that that it would probably do more than enough damage to kill a LeShay. That a Hellfire missile has been statted out by someone as 15d6 just goes hand in hand with my contention that modern weapons in D20 have their damage seriously nerfed...probably to 1) keep the rules consolidated and 2) to facilitate viability of mixed-genre games.
Those damage totals are quite in line with the stats for vehicles provided.
330 Foot Luxury Yacht: 94 HP and Hardness 5
M1 Abrams Tank: 64 HP and Hardness 20
UH-60 Blackhawk: 46 HP and Hardness 6
V-22 Osprey: 52 HP and Hardness 5
Humvee: 38 HP and Hardness 5
Ford Crown Victoria (typical police car): 24 HP and Hardness 5
With stats like those for vehicles, the damage given for heavy weapons are quite reasonable for destroying them (remembering that destroying them does not mean completely reducing them to scrap, the same way that reducing a person to 0 HP means reducing them to a bloody pulp, that's the amount of damage to totally incapacitate the vehicle).
We are used to playing PC's with HP totals like that, but they are the outliers, remember that a typical person has typically between 2 to 7 HP depending on the details (1st level D&D commoner with 1d4 HP would have 2 or 3 on average, 3 or 4 if he was an Expert instead of a Commoner. 2nd level d20 Modern ordinary with 2d6 HP would have about 7 on average). Don't let the sky-high HP totals of those rare PC's skew your understanding of how tough (or not) most people and things are.
The extrapolation that a weapon can kill a LeShay because it can take out a tank is like saying a weapon can kill Lolth (a being with similar HP and DR) because it can kill a Mummy in one hit (a being with DR and similar HP total).
IEDs can be very powerful.
You may note that some IEDs are made from scavenged military munitions, and that devices like the the OKC truck bomb that took out the Murrah building are considered IEDs.
And, FWIW, that particular IED has proven it can toss & shred a multi-ton armored vehicle quite a distance- equivalent to or superior to certain kinds of military munitions.
I know quite well the capabilities of IED's. I've lost friends to them.
However, that being said, I know that the particularly dangerous ones like EFP's are very time consuming to build, take expensive and detailed components, and highly skilled bombmakers to achieve effects similar to what we can mass produce.
The VBIED used in OKC was a huge outlier in IED construction. Even then, saying it could do 800+ HP of damage seems very out of line with the damage of other heavy weapons and HP totals of vehicles.
