Think about it. Back around 1920 Federov was developing what was to become the first assault rifle based on the smaller 6.5mm Japanese cartridge. They were the first to adapt a semi-automatic rifle (Simonov AVS which preceded the Garand). In 1939, work began on an intermediate cartridge and this led to the now famous 7.62 x 39mm. Postwar when the U.S. struggled with developing the M14 and its successor, the M16, the Russians got it right the first time with the AK-47. Now, while we continue to equip our troops with a modified M16, the Russians concluded that with the AK-74, the design could not be developed any further and superceded it with the indirect impulse operated AN-94. Underwater weaponry? I doubt if we have anything close to what the Russians have.
Now, before anybody gets upset, I prefer the M14 (TRW of course) over the AK, and would not feel uncomfortable with the M16 (or AR). The concern I have is that we shouldn't be too smug with ourselves or dismiss the ingenuity of the Russian designers or their industry.