IF YOU thought Dolly the cloned sheep had an ill-starred life, spare a thought for her fellow ruminant Shaboom. This hapless yet aptly named ram was fed recycled explosives as part of a project to find commercial uses for the many tonnes of explosives in the US that pass their 鈥渦se-by date鈥� every year.
Happily for Shaboom, who did not live up to his onomatopoeic name, it turned out the idea of feeding nitrogen-rich, gunpowder-derived supplements to livestock was not commercially viable. But recyclers have found a better use for their redundant explosives: in 鈥渟tealth bullets鈥�.
Gunpowder is a granulated mixture of potassium nitrate, charcoal and sulphur. A stabilising compound is added to the mix to protect it from the effects of moisture, and extend its shelf life. But every year some 100,000 tonnes of bullets and gunpowder in the US become too old to use safely, adding to a 500,000-tonne stockpile.
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The Pentagon manages to dispose of 100,000 tonnes a year, mostly by burning it or blowing it up. 鈥淭his, you can imagine, is environmentally questionable,鈥� says Hap Stoller, president of materials research firm TPL of Albuquerque, New Mexico.
His company has long been involved in finding 鈥渇riendlier鈥� ways to dispose of gunpowder, mostly by turning it into blasting gels for the mining industry. But now it has discovered a way to recycle gunpowder so that it produces much less 鈥済un flash鈥� and smoke when used in bullets. This will help soldiers to be more stealthy and avoid the temporary blindness caused by the flash.
Gun flash happens when gunpowder fails to burn up completely inside the barrel but instead glows or burns in the air, or when temperatures are so high that the gaseous products of the explosion ignite.
Although TPL is keeping secret precisely what it does to the old gunpowder, according to research manager Rick Snow the firm changes the physical properties of the grains of explosive so that it burns more quickly or emits more light in a non-visible part of the spectrum.
But Bruce Watkins, an expert in explosives at the Lawrence Livermore National Laboratory in California, says he can guess what TPL does. 鈥淭hey probably grind it up, dissolve it, add more stabiliser and re-certify it for use. It鈥檚 a fairly involved process.鈥�
Using its own firing range, TPL has perfected the low-flash gunpowder formula for bullets used in .45 calibre pistols. In firing tests with the Albuquerque police SWAT team, TPL says officers were between 30 and 40 per cent faster at engaging targets in the dark when using the recycled bullets compared with standard ammo 鈥� thanks to a faster recovery of their night vision. The powder is now being evaluated by the US navy.
鈥淲e鈥檙e all trying to get rid of traditional methods of disposal for environmental reasons,鈥� says Ian Moore, a demilitarisation specialist with British defence lab Qinetiq in Foulness, Essex. 鈥淚t鈥檚 something we鈥檇 like to do over here.鈥� But in the UK the market for bullets and blasting gel is too small to support the cost of recycling right now, he says.