Reloading 9mmp - Part2

Warning – this will only apply to 9mmp loads as it is by far the most reloaded cartridge in SA. Loads discussed are my own. Do not copy them, do a proper safe load development.

Part2 – Priming

In part one we covered what happened to the case when fired, why we have to resize it and the steps to resize successfully.

Now we need to prime the resized case. But first let’s take a look at how a primer works.

Here is a simplified version of what happens in a primer:

·         Firing pin pushes into primer cup at base of cartridge.

·         Cup squeezes priming compound into anvil.

·         Pressure created causes priming compound to ignite.

·         Ignition moves through flash hole or flash holes.

·         Powder is ignited… you know the rest...

You get 2 types of primers; Berdan Primed or Boxer Primed.

What is a Berdan Primed Case?

American inventor and U.S. Army Major General Hiram Berdan invented Berdan primers. Berdan primed cases have two flash holes. When you look at the section of metal on the casing between the main body and the primer recess, you will see two flash holes instead of one. The primer does not have an anvil…the anvil is part of the case.

What is a Boxer Primed Case?

An English inventor named Edward Mounier Boxer invented Boxer primers in the 1860’s. Boxer primed cases have one flash hole at the very centre of the case. When you look inside an empty case you will see a small hole between the primer recess and the powder space. This flash hole is at the very centre of the case. The anvil is part of the primer and not the case.

You want Boxer Primed cases to reload.

A very important part to note is that a primer does not need a sharp object to pierce it to ignite; the primer compound just needs pressure to ignite. Just crushing a primer will ignite it, so next time you hear me say do not force a press, remember this bit of info.

And that a Berdan primed case can ruin a reloading session. A normal reloading setup will not remove a Berdan primer and if a Berdan primed case is forced it will break a decapping pin.

Check your cases for these and discard them. Yes you could convert them but it’s just not worth the effort for a regular reloader.

9mmp uses a small pistol primer - SPP. There are lots of makes on the market and most will do the job. As you progress in your reloading journey you will find your favourite make but in the end you will just use what you can find.

Just note that some are hotter than others and this could influence your velocity…again more on this later.

Popular makes in SA is S&B, Fiocchi, Winchester etc. Just make sure that before you leave the shop that you have Small Pistol Primers and not Small Rifle Primers….the S&B boxes are identical and you need to have a close look. Small Rifle Primers are much harder and will lead to frustrating days on the range.

Now your old primer was “decapped” or removed by the decapping pin in the sizing die. You can choose to clean the primer pockets now but if you are like me you will skip this cleaning part…I have never cleaned a primer pocket and personally feel there is no need. Cleaning the primer pocket can be done with a Lee primer pocket cleaner.

So how do you prime your cases? Well that depends on your press and set up.

Single Stage and Turret presses can be fitted with the Lee Safety Prime system. This is one of easiest and best on press solutions you can use. This system allows for your resized case to be primed on the down stroke after sizing. All you need to do is align the trigger and add a primer to the priming arm. Then complete the down stroke. The priming arm then inserts the primer perfectly.

On the Pro1000, primers are loaded automatically. The priming system will add a primer on the primer pin and when you complete the down stroke after sizing the primer pin inserts the primer.

The Load Master works much the same way as the Pro1000 except that the priming happens on the up stroke.

 The other option is to hand prime. This is done with a hand primer or a bench primer and done off the press.

Lee also now offer a dedicated priming press called the ACP...if you are hand priming you should look at this press.

Whichever way you do prime your cases make sure that you seat the primer flush. Primers not seated flush will not ignite. What happens most of the time is that the primer pin/striker will seat the primer rather than igniting the primer. High primers can also lead to feeding issues.

You also do not want to seat your primers too deep, a smiley on the primer is a dead giveaway that the primer is seated to deep. With most priming systems you cannot do this but with a Load Master you can seat your primers to deep.

The important bits you need to know about priming.

·         Inspect your cases for Berdan Primed Cases.

·         Crushing a primer will ignite it.

·         Seat primers flush. Do not short stroke the press.

·         Use the correct primer.

Up next we look at case flaring …