... The Soviets gave up trying to make the SVT a sniper rifle after 2 years ...
The downfall of the SVT as a Sniper had more to do with economics and production pressures. The Mosin was very much a known quantity for a sniper platform, they'd worked out all the bugs years before the war even started. And the selection process for "sniper" versions for both rifles was the same - as they came off the line and were measured for tolerances and test fired, ones that met quality and accuracy criteria for a sniper variant were set aside for conversion.
SVT production, even at its height, never even approached a small fraction of the number of number of Mosins being produced. Keeping to a known quantity and standardization during war production is a bit of a no brainer.
Not saying that the SVT is the be all to end all, but there was potential there that the Soviets just didn't have the time or resources to explore given the pressure they were under to put boomsticks in as many hands as possible as quickly as possible - raw economics favoured the Mosin.
And the SVT didn't just disappear after the war... While the SVD is an almost entirely original design, it draws much design philosophy from the SVT... Short stroke gas piston semi auto with a ten round detachable box magazine, muzzle brake to control recoil for faster follow up shots...
I think the potential of the SVT falls into the "What if..." category. What if they'd had the time and resources to refine the concept. What if they didn't already have such a well known quantity in the Mosin. What if production pressures were low enough that they could have ensured each was properly bedded in the stock (the problems with the stock are among the key complaints for achieving decent accuracy with the SVT-40)... What if Stalin hadn't purged the army of so many high quality professional officers before hand and kept training levels of the army as a whole at a level where the average grunt would have had the skills to properly maintain the rifle (the Wehrmacht grunts put it to better use than the Soviets ever did)...
Not picking a fight, in any way. I just find it to be one of those interesting questions of history. Military history is littered with squandered opportunities due to short sightedness or economics. "The best platform will win out..." is actually very seldom the case in military procurement. Usually what wins is "the best platform we can afford that gets the job done."
For the Soviets in WWII, that meant the Mosin won. It was vastly cheaper and easier to produce, and put it in enough hands, and it could get the job done. That doesn't mean it was the best possible platform the Soviets had available to them at the time.
