Incremental Loading

[horseman2]

The attached photo are loads using a 280 Remington BDL SS with a Leupold VX-6 (2 - 12 x 42).
The loads are IMR7828SSC from 56.5 - 59.0 grains and Sierra 160 Grain Game Kings and Magnum Rifle Primers.
The velocities are also posted.
On test day there was enough fog that load 4 and 5 could not be seen at 200 metres but more testing is in line.
No pressure signs so will try 58.5, and 59.0. Yes I am aware this load is 7 grains above the Speer Maximum.

When sighting in the new scope at 100 yards, the load was 58.5 grains of IMR 7828 and 160 grain Speer Mag Tips. One shot over a Chrony showed 2884 fps.

 

[horseman2]

These are the loads using the same powder charges but with the Speer 160 Grain GS.
The Ballistic Coefficient is better with the GS over the Mag Tip but the Sierra is best.
I was only able to see shot 1 & 2 but the 3.5 inches the other 4 fall into are acceptable with 1.5 grains variation in the powder.
Also shot at 200 metres and the snow in behind the target was no better than the fog.

 

[labrador76]

Curious why you are using magnum primers with a standard caliber? Does it have something to do with the large charge?

 

[horseman2]

Curious why you are using magnum primers with a standard caliber? Does it have something to do with the large charge?

IMR7828 has pretty slow burn rating and the Mag Primers appear to be a better igniter.