There are many parameters involved in producing safe, accurate ammunition. Case length, powder charge, bullet shape, body diameter; all can enhance or ruin accuracy equally. However, headspace — the distance from the base of the cartridge to that point which prevents the cartridge from moving forward any further — is one parameter that can often be overlooked, yet is totally controllable. For rimmed cartridges, the head-space is controlled by the thickness of the rim; and some of our belted magnums — the .375 H&H, the .458 Winchester Magnum and the.458 Lott come quickly to mind — still head-space off of the belt instead of the shoulder. But, for most of our common bolt-action calibers, the shoulder position controls the head-space dimension.
I’ve come across some rifles that have had headspace…