The original rumor was that McVeigh was trying to buy hydrazine to supercharge the explosive. This is "rocket" fuel, a hypergolic monopropellant, C2H4, invented back in the 1930's by der Germans. The ammonium nitrate used by McVeigh and company was not up to the strength necessary for a real explosion. Talk with a master blaster, or someone who really knows the math involved and you will soon learn the explosives supposedly used would blow out windows but couldn't possibly have done that much damage to the building from that distance. The jaw flapping about a "shaped charge" is pure BS. McVeigh, or his co-conspirators, had they used this homebrewed superexplosive for a peaceful purpose, would have qualified for a Nobel Prize in physics.
Do the math....