"Ancient bolt-action rifle. Probably pulled from a basement somewhere. Good range, good power, low rate of fire."
A slow-firing rifle able to take out targets at longer ranges. In close quarters combat, its slow handling makes it less valuable than a machine pistol, a pump shotgun or even a pistol, but a colonist armed with a survival rifle has the ability to accurately damage enemies from distant cover and maintain distance between themselves and the enemy, forcing those armed with shorter-ranged weapons to close range before they can retaliate.
A survival rifle, a pistol and a knife (plasteel) can be found at the crash site at the beginning of the game. True to its name, this rifle is absolutely ideal for hunting down wild animals like muffalo and deer for their meat and skins, as it has plenty of range and power for killing them quickly and efficiently.
Unfortunately, the survival rifle out-ranges improvised turrets, often forcing colonists to expose themselves to take out a rifle-armed raider in an open battlefield. For this reason, it is recommended to build sturdy fortifications at the furthest extreme of a turret's range, to force raiders into their killing zones.
As with all ranged weapons, it is important to make sure that enemies armed with melee weapons do not engage with your riflemen. Otherwise, they won't be able to fire at all! This applies to enemies as well, so engaging enemies with rifles in melee combat is a good way to nullify their threat quickly.
Fun fact: The Survival Rifle has the highest average accuracy of all the weapons (~89%), and outclasses even the sniper rifle in terms of long-range accuracy (88% vs 90%).
The survival rifle used to be called the Lee-Enfield in older versions of RimWorld. In real life, the Lee-Enfield is a reliable and powerful bolt-action, magazine-fed, repeating rifle that was used primarily by the British military in the early 20th century, notably during World War I and II. The Lee-Enfield had a 10-round magazine (loaded with 5-round "charger clips") and used a .303 caliber (7.7mm) cartridge.