A sniper rifle is a type of long rifle which is designed to engage targets at extreme distances. Most sniper rifles make use of high-caliber ammunition, although this is not necessarily the case, and are typically designed to allow the user to make high-precision shots. Before the advent of assault rifles, sniper rifles were typically no more than common bolt-action or semi-automatic battle rifles with an attached scope and other minor modifications.
A bolt-action sniper rifle is a sniper rifle that utilizes bolts that are operated manually by the opening and closing of the action with a small handle, most commonly placed on the right-hand side of the weapon. In the series, they are immensely powerful and capable of killing an enemy in one shot. Despite this, they tend to have a slower rate-of-fire due to their bolt-action design.
A semi-automatic sniper rifle is a rifle which makes use of an automatic rechambering system. These tend to be more common in Battlefield games set in the modern-day. In game terms, the semi-automatic rifles tend to be designed for shorter ranges than the bolt-action ones, and are also niched into less-damaging groups.
A fully automatic sniper rifle is one in which the weapon fires and recharges several times without removing the user's finger from the trigger. This is a much less common firemode than either bolt-action or semi-automatic, and only appears on the VSS in a few games, and the SVU-A in Battlefield Play4Free.
Semi-Automatic Sniper Rifles have somewhat changed in role in Battlefield 4, as most of them are now available to all classes as Designated Marksman Rifles. The exceptions are the SR338, which is more powerful and with longer effective range than DMRs, and the M82A3Battle Pickup, with power greater than even bolt-action rifles.
Sniper rifles in Battlefield 1 are better described as single-action rifles that can deal high damage at long range. However, not all single-action rifles have variants that come with high-powered sniper scopes, though most will still have alternative variants with medium-powered scopes.
Some self-loading rifles also have Marksman or Sniper variants that come with high-powered scopes, making them sniper rifles in a sense.