No Steel Core
It should be noted that there is a common misconception that much of the 7.62 Tokarev surplus ammunition commonly found on the market uses copper-coated mild steel bullets.
The myth states that this increases the chances of dangerous ricochets when fired at hard targets and can damage the bullet traps often used on shooting ranges. The importation of 7.62x25 cartridges loaded with copper-coated steel bullets into the USA would be illegal, as federal law defines these as armor-piercing pistol ammunition.
These projectiles are actually lead-core projectiles with copper-washed steel jackets, and present no greater risk of ricochet than a standard copper-jacketed projectile.
-http://en.wikipedia.org/wiki/7.62x25mm_Tokarev
PS. Magnet Test would not determin anything, because it would pick up both steel-core, and led-core with copper-washed steel jacket.