I think the most overlooked aspects of load development are:
1. Shifts in the shooting position, even as minute as moving from the top row of dots/diamonds to the 2nd and subsequent bottom rows if working it like reading a paper, from Top Left down to Bottom Right.
2. Muzzle velocity changes due to the shooters upper body mass recoiling differently than the original position on the first dot.
We know that position and shooter upper body mass affect muzzle velocity, so a lighter weight shooter will see much wider ES in their measured velocities and attribute that ES to components, load procedure, chamber temp, etc.
Without a fixed mechanical rest, the best position to do load development is prone, front and rear bag supported, squared-off on the rifle, not cocked to the side. Place as much as your body mass behind the rifle to resist recoil and the muzzles physical location relative to the shot when the projectile leaves the barrel.
A scrawny shooter will have significantly more rearward displacement of their upper body, which means the muzzle is physically moved rearward more as the bullet exits.
A larger, firmer upper body mass shooter will maintain muzzle position better, and therefore tighten ES, experience less disturbance to the position, which helps with positional repeatability and grouping.
1. Shifts in the shooting position, even as minute as moving from the top row of dots/diamonds to the 2nd and subsequent bottom rows if working it like reading a paper, from Top Left down to Bottom Right.
2. Muzzle velocity changes due to the shooters upper body mass recoiling differently than the original position on the first dot.
We know that position and shooter upper body mass affect muzzle velocity, so a lighter weight shooter will see much wider ES in their measured velocities and attribute that ES to components, load procedure, chamber temp, etc.
Without a fixed mechanical rest, the best position to do load development is prone, front and rear bag supported, squared-off on the rifle, not cocked to the side. Place as much as your body mass behind the rifle to resist recoil and the muzzles physical location relative to the shot when the projectile leaves the barrel.
A scrawny shooter will have significantly more rearward displacement of their upper body, which means the muzzle is physically moved rearward more as the bullet exits.
A larger, firmer upper body mass shooter will maintain muzzle position better, and therefore tighten ES, experience less disturbance to the position, which helps with positional repeatability and grouping.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com