Several points:
1. Wolverine are good folks to deal with.
2. Surplus ammo is surplus for a reason: it is no longer needed and the primers are getting dodgy. That's why it cruds up your rifle and shoots all over the barn.
If you want to shoot cheaply, get a loading outfit, a crate of surplus, about 200 fresh brass cases and switch over the LOADS from the surplus ammo to the new cases. The bullets are good, the powder charges are good; what are NO good are the Primers. You won't "shoot the sh!t" out of the rifle, either, and you might even become a decent shot with one.
3. The bog-stock SKS is about as trouble-free and SOLID as it is possible to build a rifle. They have been used by dozens of armies and by many more "freedom fighter"/insurgent and terrorist groups. The Viet Cong made excellent use of the SKS. There is NOTHING you can do to "improve" it, so save your money.
Hope this helps.