I don't believe in inherent accuracy. There may be a couple small variables that help, such as a shoulder angle and short powder column that promotes a more consistent ignition and pressure. A cartridge that fits in a short action will have the advantage of a stiffer action. A case with shoulders can be properly head spaced and centers better in the bore.
Aside from that, there is not a lot of difference between cartridges. And to realize the advantages of the above is above is good for a couple hundredths moa.
