I am building a gun but i am not sure about a few things to start with is there any difference in a 6.5-284 norma ,winchester,hornady, if so what? i would like to put a hart #5 barrell and i plan to shoot 140 bergers vlds through it. what twist 8 or 9. also what throat lenght. I am not building a bench gun so i wong go for the neck tension standards like the 1000k shooters.it will probally be a 299 or 300 no turn neck. this gun will be along range hunting rifle and milk jug killer. what are your opinions and thoughts on this. thanks any help appreciated