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

Originally Posted by Moa Hunter

In my 270 the jam point is .285" further out than factory ammo seating depth.
I gained nothing in accuracy by seating 140 AB's .015 - .020 off the lands and think like other posters have written that I should go to factory length as a start point.
From what I have read the bonded bullets are better with a .050 jump and the non bonded bullets .010 ish. Makes it confusing.
I have found AB's to be great bullets, always a pass through with a big glob of blood on the ground. The animals will often run a few metres with blood pouring out but I have never lost one. The AB's open fast and the wound looks like it's been cut with a hole saw.
There is a bloke on the forum @Pongo who probably shoots more deer than anyone here and he uses the 168 Berger in a 7mm Saum or WSM near and far.

Have just bought a set of comparators so i’ll be able to compare the distance off the lands between my loads and the factory ammunition

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.