Weight Sorting Primers – Is it worth it?

If you shoot long range you probably already know that minimising your projectile velocity extreme spread is vital. The reason is simple. If you take, a Berger 200.20x @ 2620 fps and look at the ballistics you will see that the drop at 1000 yards you will see it is 340″. At 2640 is is 334″. At 2600 it is 346″. So, if you have an ES of 40 the vertical attributed to velocity alone is 12″ or 1.2 MOA. This is larger than the size of the bull.

While there are a large number of factors that impact on ES one that gets forgotten is primers. The primer starts the ignition process and we know that ignition generates our peak pressure. We know a half-full case will have erratic ignition but what is the impact of a half-full primer?

It may surprise you to know that primers are hand made in that the priming compound is hand wiped into a set of holes in a plate and from there deposited into the cup. There is some variation between the quantity of primer compound in each primer and with that some variance in the pressure wave it creates.

Here is an article that looks into the correlation between primer weight and the primer pressure wave.