It’s bogus, the standard rifle of the Russian forces is the AK-74, developed in the 1970s. Their main tank is the T-72 developed in the 70s but continuously developed and upgraded since. Most of their attack helicopters date from the 70s and 80s or later.

That may all sound dated, but bear in mind the M4 rifle used by US troops is based on a 60s design and the Abrams M1 tank is basically a 70s design. The Russian forces have been comprehensively re-equipped and resourced over the last decade and have experience from operations in Chechnya and Syria.

Even if true pre WWII era ammo is often found by sportsmen and tested, it works just fine. Modern shell design which is over 100 years old doesn't degrade with time very much.

New ammo is more reliable of course, but old works well enough if you have a gun to use it in.