There is a big push in the U.S. Army and Marine Corps to get a sniper rifle that can consistently get kills out to 1,800 meters. The current 7.62mm round is good only to about 800 meters. There are three options available here. The most obvious one is to use a 12.7mm sniper rifle. But these are heavier (at 30 pounds) and bulkier than 7.62mm weapons, but can get reliable hits out to 2,000 meters. Another option is to use more powerful, but not much larger round. For example, you can replace the barrel and receiver of the $6,700 M24 sniper rifle for about $4,000, so that it can fire the .300 Winchester Magnum round. This is longer (at 7.62 x 67mm) than the standard 7.62x51mm round, and is good out to 1,200 meters. Another option is to replace the barrel and receiver of the M24 sniper rifles to handle the .338 (8.6mm) Lapua Magnum round. Thus you still have a 17 pound sniper rifle, but with a round that can hit effectively out to about 1,600 meters.
Snipers in Iraq, and especially Afghanistan, have found the Lapua Magnum round does the job at twice the range of the standard 7.62x51mm round. The 8.6mm round entered use in the early 1990s, and became increasingly popular with police and military snipers. Dutch snipers have used this round in Afghanistan with much success, and have a decade of experience with these larger caliber rifles. British snipers in Afghanistan are also using the new round, having converted many of their 7.62mm sniper rifles.
Recognizing the popularity of the 8.6mm round, Barrett, the pioneer in 12.7mm sniper rifles, came out with a 15.5 pound version of its rifle, chambered for the 8.6mm.