The bullet itself has no steel content. The case itself is the only thing that is made of steel. The bullet is a non expanding fmj with a lead core. U will not damage anything shooting a NATO round out of a civilian 308 rifle. If the bullet contained a steel core it would be considered armor piercing and would be illegal to sell, own or use in Canada. Carefully re read what the description says on the box of Barnaul ammo.
You're wrong on pretty much all points.
The bullets in Barnaul are usually bimetal but without a steel core. That means a mild steel jacket with copper coating the outside and a lead core.
You will sometimes find some with true copper-only jackets. Same goes for Tulammo; it's whatever they had at the time to use.
Steel core and steel jacketed ammo is not necessarily armour piercing and tonnes of it is sold in Canada every year. It is not illegal in any way.
A mild steel core is for cost savings, not armour piercing. You will find it on a lot of Soviet surplus and even US made 5.56NATO 62gr green tip ammo. It is not classified as armour piercing.
A mild steel jacket is also for cost savings, not armour piercing. Copper is several times the cost of steel at current market values. Lead is also more expensive than steel.
A steel tip can cause a bullet to tumble when it hits a target causing more damage. So when expanding bullets where banned in war many looked for ways to increase damage without expanding.
Armour piercing ammo needs to have a core or tip made from hardened steel, tungsten carbide, or another steel-cutting material.
Armour piercing rifle ammo is not illegal in Canada. Only armour piercing pistol ammo is.