Generally accepted as the world's first assault rifle, the StG44's effect on post-war arms design was wide-ranging, as evidenced by Mikhail Kalashnikov's famous AK-47, and later in the U.S. M16 and its variants. The Soviet Union was quick to adopt the assault rifle concept. The AK-47 used a similar-sized round and followed the design concept, but the AK was mechanically very different.
Sturmgewehr 44 - Wikipedia, the free encyclopedia

I'll admit its mechanically different but the design and concepts are very alike.