neck tention and muzzle velocity

[blackfly]

I've searched some of the old threads and found alot of info on neck tention but nothing on its effect on muzzle velocity. How much effect does verying neck tention have on velocity? I'm talking in general terms here and I'm only looking for a general answer. But for an example ,how much in ft/sec, say when your looking @ 2990 '/sec with a .300 WSM could you see because of inconsistancy? With all things concidered to be equal in your reloading proceedures could or would that be a primary cause to look at when a round gave an inconsistant reading on your chronograph in a outherwise consistant string of rounds ?