Riflemen are the most versatile position, and fill in when a specialized player has been eliminated. Perhaps ironically, veteran riflemen are virtually the direct opposite of newbies described above, in that they characteristically are competent in virtually every style of paintball play, travelling by themselves, instead of moving with other riflemen in a squad.
Experienced riflemen may also follow a specific style. For example, a rifleman may choose to be something like the gunner specialist position. Gunners mostly carry many paintballs and move much slower than a normal rifleman would. This rifleman may carry more ammunition than others, and may wish to choose a barrel that extends the range, but not necessarily accuracy. Gunners are called upon to fire at the opponent, not to hit, but to keep them behind cover so that other members of his team can flank them. This rifleman would be the best choice to fill in if a gunner is eliminated.
Because a rifleman may choose to follow a specialized form of the position, there is not always a clear-cut guideline for the position. Thus, a quicker rifleman may want to adapt his gearkit and his marker to be lighter-weight and higher in profile, to benefit their close quarter game. However, riflemen would generally use a balanced gearkit so that, when called upon to fill in an eliminated position, would not be too bulky for a faster position, but with substantial ammo to fill a position requiring much paint. Woodsball riflemen may want to use a "remote" air system, that is, carrying it on their person instead of using an on-gun system. This benefits the player by creating a lower, longer profile, thus making ducking down behind cover easier.
Many commanders also start out as riflemen and make capable commanders because riflemen can fill in any position due to their flexibility, knowing the basics of each position. This gives the commander an advantage because they know the strengths and weaknesses of each position, so they know how far each position can be pushed.