Your reply again points out my question as to why Anderson even needed to construct and deploy such improvised muntions? He certainly had enough standard munitions available to construct a very deadly defense of Fort Moultrie from a land assualt. Which again goes back to the question of his reasoning for abandoning Fort Moultrie in the first place. If he had this type of defenses in place he had little to fear from a land assualt of poorly trained South Carolina Militia, or a mob of citizens as he claimed.
The only logical reason for Anderson's constructing such improvised munitions as the "Thunder Barrels", when he had such a wealth of conventional ordinace and explosives, would have to be that the Thunder Barrel gave him some sort of advantage or desired effect, which he felt that he did not have with conventional munitions. This would give some testimony as to the precieved destructiveness and effectiveness of these weapons against an assualting enemy force.
Therefore the formation of "Thunder Barrel" battalions at Vicksburg by the Confederates may not have been as much a last ditch act of desparation as you would at first be lead to believe. But in fact a proven defensive tactic against assualt troops.