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.

T72 is a 60s design too

It’s literally named after the year it went into production. Of course it was a product of iterative design, refinement and experience going back decades.

122mm ammo - WW2 stocks still there, 7.62x54R - same, 82mm mortars ammo - same, earliest KPV ammo is just few years older.

Old tanks as no match for modern MANPADs

I think you mean antitank rockets & missiles. MANPADs - Man Portable Air Defense weapons - are for use against helicopters.

sorry, generic misused term. In this case I meant javelin and the UK/Swedish equivalent. Both of which have been supplied to Ukraine.

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.

Yup, I've fired plenty of WWII era 7.62x54r out of my M91/30. No issues with it ever.