Smooth-bore weapons, such as the musket, had always been recognized as relatively inaccurate, especially at longer ranges, and required massed volleys to be combat-effective. Although the smoothbore barrels impeded the accuracy of a musket, it was an advantage when loading because the looser fitting musket ball slid down the barrel quickly and easily with the ramrod being used mainly to compress the powder charge at the base of the barrel. Rifles required a tighter fit and thus more work to get the ball to be rammed all the way down the barrel. This meant that the soldiers chosen for this role needed to be good shots, resilient, brave, and resourceful. Riflemen were trained to act in isolation and were dispersed in teams of two, defending each other while they re-loaded. They were still vulnerable, especially to cavalry, as they could not present the solid wall of bayonets a larger mass of soldiers could. These factors: the time and expense required in training, the limited number of suitable recruits, and the specialized roles and situations where they were most effective meant they were highly prized, given special privileges, and used sparingly rather than squandered.