ak-47
The AK-47 (Автомат Калашникова образца 1947 года) is a 7.62×39mm assault rifle of Soviet origin, developed between 1944–1946 by Mikhail Kalashnikov. The AK platform has a reputation for its ruggedness, reliability, simple mechanism and ease of manufacture. It can perform well with poor quality ammunition and under harsh conditions.
Visual cues of the original AK-47 are its slanted fixed buttstock profile, a milled receiver with a large rectangular indentation as the magazine guide and a smooth dust cover, (see Danbooru post #4852784).
Do not simply tag any Kalashnikov rifles as AK-47 without even looking at their details.