The US military's project intended to produce miraculous sighting systems for sniper rifles - designed to ensure that million-to-one shots will actually be almost certain to hit their target, rather as in Terry Pratchett's Discworld stories - has moved forward. American weaponry behemoth Lockheed has been awarded a $6.87m contract to produce "fully operational and field hardened systems" following successful brassboard tests.

One Shot, which we reported on earlier this year, is planned to consist of an enhanced scope instrument to replace the telescope traditionally used by the spotter of a sniper team. Rather than a simple optical affair, perhaps combined with an ordinary laser rangefinder as used today, the One Shot gadget will also measure temperature, air pressure, humidity and elevation of the target. Better still, it will use a laser beam to measure the wind's direction and strength not just at the sniper team's location but all the way downrange towards the target.

All these factors will be integrated instantly in the One Shot spotting scope's onboard computer and used to generate a set of crosshairs in the sniper's telescopic sight, linked to the scope either wirelessly or by a cable. The artificial crosshairs will show where the bullet will actually strike, rather than merely where the weapon is pointed, and there will also be a readout showing how likely it is that the wind will change during the bullet's flight and how big an effect that will have - so allowing the sniper to choose the right moment for a shot.

All this will allow a sniper team to make first-shot kills reliably at ranges of 1500m, almost a mile. Various snipers have surpassed this range - the current world combat record is generally thought to be held by Corporal-of-Horse Craig Harrison of the Household Cavalry, who killed two Taliban machine gunners at a distance of 2,474m last November. But Harrison himself admits that the conditions were freakishly kind (no wind, mild weather, clear visibility) and he had to shoot and miss several times before getting the necessary corrections nailed down. The previous record-holder, Canadian Rob Furlong, likewise needed several rounds to get on target for his 2,430 kill in the Shah-i-Kot valley in 2002.

In general, the British Army doesn't expect its favourite sniper rifle, the L115A3 (aka the Arctic Warfare Super Magnum from Accuracy International of Portsmouth), to deliver one-shot kills further away than 600m, with "harassing fire" to 1100m. Under normal circumstances, the difficulty of estimating environmental corrections, especially the wind, is just too great.

But in brassboard tests of the One Shot system, US military officials say that their prototype computer scope has pushed the limits back.

Under all test conditions, the brassboard system significantly improved the first round hit probability, required fewer rounds, and less time to get the first hit vs users without the One Shot system

Under yesterday's $6.87m contract award, Lockheed will turn the brassboard system into a field-ready unit. Fifteen of these will undergo further trials with military sniper teams, and the tech will then be tweaked and enhanced still more before another 100 One Shot systems are produced.

Ultimately, One Shot programme chiefs expect that any sniper team equipped with their kit will be able to make one-shot kills six times out of 10 or better out to 1500m regardless of crosswinds etc, using any of the normal types of ammo currently used by US and British snipers: namely .300 Winchester magnum, .338 Lapua magnum and ordinary 7.62mm NATO.

Such shots would normally be seen as well-nigh miraculous, so of course on the Discworld they would hit nine times out of ten. (Six is perhaps close enough.) The One Shot technology, if it works, would seem likely to deliver something of the Pratchett Effect to the real world. ®