Thread: Load Testing Analysis. What do i make of this?

Powder weight seems to be one of the less important factors in accuracy.
People do chase the fabled "nodes" and "most accurate powder charge" but in my limited experience point of impact and group size don't change much with powder weight. So what you're seeing is very common.

It's a good idea to buy a box of factory ammo with components similar to what you'll reload and shoot a 5 shot group of it each reload testing session as a control. Generally, reloads will at least match factory ammo and if they don't you will have a problem with your equipment or process which you can fix.

Two key factors are cartridge headspace and concentricity.

7RM was designed to headspace off the belt but in practice it has to be off the shoulder so get a shoulder insert for your comparator and see how much you're sizing them down each time. Adjust the die til its around 0.003". 7RM loaders can confirm if that's right for that cartridge. My smaller cartridges are 0.003" and 0.001" shorter after full length sizing, which is all I do.

Concentricity is said to be the most important thing. Perhaps your sizing or seating die isn't sitting straight in the press. Or the die you have is a dud. Use lube on the inside neck or expander ball. Others may be able to suggest how to investigate or correct this.

Trimming brass to length, squaring the mouth and a gentle chamfer may also help bullet seating.

Start by expecting to shoot deer at 300m. 500m is too far, even with a magnum. Until you've done a lot of target shooting with it.