I'm building a new rifle with Lawton 400x action and Lilja Barrel a 284 Winchester Improved. Along with my gunsmith we'll design a chamber reamer with a 40 degree shoulder angle (instead of original 35 degree) and less body taper, approximately .010" (instead of original .025" of body taper). Essentially an ackley improved design.
The reason for this round is to ease in the extraction of fired case (similar to the 284 Shehane) and split the difference between the 7mm-08 and 7mm WSM. With a 28" barrel and Reloader 17 I'm hoping to get a 180g. Berger VLD moving close to 3000fps.
Would you choose to fireform Winchester brass or neck up 6.5-284 Lapua brass? On the 6mmBR website (260 Ackley Case Forming
) a tech article where the author was fireforming 260AI brass from necked up Lapua 243 winchester brass. He was running into donuts being formed at base of neck. Perhaps using winchester brass that does not require necking up would eliminate this donut problem.
Your thoughts on brass selection please.