The SVT is a proven design, strong enough to handle the 7.62x54R. The gas regulator while adding complexity to manufacture, permit the rifle to function in any conditions with pretty much anys ammos hot or unpowered war time stuff. The snipers and elite troops made very good use of it, even the german,who liked it so much, made a manual for the large amount of captured SVT. The russian dropped the production mainly because was a complexe rifle for the average conscript and also, required more time to manufacture the the Mosin, the russian needed huge amount of equipment for the ever growing army so mosin and submachine guns were way easier to make than the Tokarev rifle. On another note, the automatic version of the SVT, the AVT 40 did not have success because of increasing part breakages, the 7.62x54R was to powerfull to be fired in automatic mode since the Tokarev is a pretty light rifle if you compare to a Garand. All that said, the SVT was the second semi auto rifle,after the Garand, to be issued in large quantity, at the time the Tokarev was a important step in the semi auto battle rifle development.
Joce
Joce
Put the SVT side by side with the FN 49 and you' ll have to conclude the latter, which is similar in most respects, is way better built for a combat rifle. 
