smokeless powder, velocities well in excess of 1000 ft/s (300 m/s) were produced from handguns for the first time. At these velocities and pressures traditional soft lead bullets would quickly foul the barrel with lead deposits, so gas checked bullets were used in these experimental cartridges. The other common use of gas checked bullets is in obsolete military rifles. Many of these rifles used calibers that were unique to the rifle; low levels of commercial production and dwindling supplies of surplus ammunition quickly result in high ammunition prices. Many of these rifles use unusual bore diameters; for example, both the British 7.7×56mmR and Soviet 7.62×54mmR rifle cartridges use bore diameters larger than US .30 caliber (7.62 mm) standard bullets, resulting in a much smaller supply of suitable bullets—often just a single full metal jacket bullet design in the weight used by the military loading. Custom made bullets also allow the bullet to be carefully sized to match the bore, which can vary considerably in surplus rifles, and provide both more accuracy and more flexibility. Gas checks allow these bullets to be pushed to higher velocities without undue fouling of the barrel and attendant problems. See also Driving band Sabot References Handloading Firearm terminology