7.62 x 39 surplus ammo comparision questions

[Robert Nicholson]

I can hit a big shaped gong very regular with my 1950 refurb sks bone stock with iron sights.
Can't hit quite as well with my 1954 non refurb.
My vz58 is deadly accurate with the Czech surplus.

My 1950 refurb is also my most accurate SKS. It still has its original barrel which is not chrome lined. I am wondering if that has much to do with its accuracy?
Or does a non chrome lined barrel just have a small, hardly noticeable advantage and the accuracy of my 1950 comes from other things?