Tell us about yourself!
Hey to anybody tempted to try this: 12 grams of black powder might not seem like a lot, but it's a lot. The ratios, compared to the classic ratios, are off a bit, too. And the last bit in step 3 about putting the ingredients into a mortar and pestle would seem to imply using the pestle (stick) to mix the ingredients in the mortar (cup)--DON'T!! BP in a open container won't boom but it will flash and burn you badly and don't even think about scaling this up to make a larger quantity.
Throw a chain around the concrete and go.
A weapon? What next a zip gun? I think this is wholely inappropriate and dangerous.