We came back from the range a week or two ago and with the cases that we’ve fired we seemed to pick up a rogue case.

In sorting En properly picked the 10mm from the pile of .40 that we shot. They are basically the same case, but the 10mm is a bit longer and it uses a large primer to set it off. Looking at it I quickly found something amis with it.

Of course that’s not what a proper 10mm. The jagged edge is a dead giveaway.

Left: Proper fired 10mm case. Right: Recovered 10mm case with a lateral split.

Looking at the primer, while not an exact science, really told the story.

This was shot out of a Glock. I’m going to presume that it’s out of a Glock 20 since I’ve never seen anyone with a 29. You can tell that it’s from a Glock because of the peculiar rectangular firing pin channel. Of course in this instance it actively flowed into the channel and completely flattened itself against the breech face as well.

Even the head-stamp shows a bit of distress.

The 10mm cartridge is really hand loader’s cartridge. It doesn’t have a lot of guns that are chambered for it as well. That being said it is a large-capacity cartridge and you can easily tune the load from a very light load to a real barrel-burner. The Starline brass is another piece of evidence since they mainly cater to handloaders. (I have seen Starline on a commercial loading from Fiocchi in .40 S&W, but I’ve never seen it elsewhere)

Putting the pieces together I can only guess that this particular case was overcharged, perhaps double-charged.

Here’s what it should look like, compared to the blown up round:

The case on the left shows no signs of the primer flowing at all. You can still see the radius at the edge of the primer as well. The head stamp seems significantly clearer as well — though that in and of itself isn’t enough to go on since I don’t have any other examples of what 10mm Starline brass looks like. Incidentally you can tell the good case was also fired out of a Glock, perhaps out of the same one. (I picked up the good case around a year ago; the broken case is from a week or two ago)

Here’s another example of a fired large pistol primer in a different (and lower pressure) case:

I don’t have any unfired factory large primer case, but they look a lot like the small primers.

All of these are from Winchester white box 9mm. Their still in their original case in this picture.

Here’s all of the fired large primers in one picture for comparison purposes.

I just wonder what happened to the gun when this round was touched off. Certainly it left some of itself in the chamber of the gun… How bad was it?

Quick and random one today. When I buy boxes for ammunition they always seem to come with stickers for the load information.

That might work fine for rifle loads when you load up 20 for hunting or something, but it seems to be a bit insufficient for pistol loads when I load up 300 in an sitting (or more!) and I reuse the boxes over and over.

That got me thinking about labels.

At OfficeMax I came across some semi-permanent labels: Post-it Labels

Here’s the template I’m using for them: Load Data Labels

I can tell you that they do go on fine, and just as importantly they come off fine too.

Here’s what I’m recording on each label: Lot Number, Cartridge Type, Powder Type, Powder Amount, Bullet Type, Bullet Weight, Overall Length, Production Date and Notes

All of these are also recorded in my log book (well, Google Spreadsheet), but it provides a great quick reference. (The log also includes things like lot numbers, and a whole bunch of other settings…)

So you know that I got myself a new gun. You can call it my birthday present if you want.

It certainly is a pretty gun. Like the classic 1911 it’s chambered for in .45 ACP.

The problem is that factory ammunition like I wrote before is frickin’ expensive. A box of 50 rounds will set me back $25 at the range. I could save a bit of money if I get it online, but the cheapest I’ve seen is around $13/50 for really cheap Russian steel-cased ammo, or actual brass ammo for around $19 for the US-made stuff. Of course you have to figure in shipping so you have to order a bunch for it to be worth while. If I order up a thousand rounds for instance I’ll spend around $0.42 per round once everything is accounted for.

Or I can roll my own for around $0.12. 

$0.082 – bullet
$0.026 – primer
$0.010 – powder

I’m not counting the case since I can reuse that over and over again. If you insist on counting that it would add roughly $0.05 per for a once-fired case.

Now of course the next thing I have to do if make some cartridges. Here’s where it gets tricky. There are several variables in play that need to be taken into account.

• Maximum overall length (OAL) for the cartridge per the SAAMI spec. This is the longest round that should fit in the magazine.
• Maximum OAL that will work in the gun that you’re using. Different guns will have different chamber, leade (the distance between mouth of the case and where the rifling starts), and rifling profiles that need to be considered. Put another way, just because a cartridge works in one gun, doesn’t mean it will work in another.
• The OAL will determine the seating depth of the bullet, which in turn determines the amount of space inside the case for the powder.
• The amount of powder that will be used for the load
• Technically the primer and case need to be looked at as well, but since I’m not aiming for maximum loads, I can safely ignore those for now. If I were making really hot rifle loads, I’d need to consider them.

The biggest factors to take into account for safety is the seating depth and the amount of powder. I wrote up a pretty extensive post a while back that shows the interrelationship between the two and how it doesn’t always make sense intuitively.

First thing to consider is the load manuals.

My collection of laod manuals

Each one has different recipes for the same cartridge. Then you go online to the powder manufacturer’s sites. Then to the crowd-sourced ones. No two agree. The .45 is an interesting round since there’s even more than one spec for it. There’s the SAAMI spec, the CIP spec (European), and then the SAAMI spec for a +P version which can take more pressure. (Some older rounds have a similar issue, 9mm and .38 special are other ones mainly)

In my case I’m going to use HP38/Winchester 231 (same thing, different label) since I have a good supply of it.

The loads I saw ranged from starting loads of 4.4 grains (7000 grains = 1 pound) to 5.6 grains. The max loads went from 5.6 to 6.5 grains. Yes, one of the max load in one book was the starting load in another.

Why?

Different lots of powder. Different test barrels. Different max pressures (remember normal vs. +P) Different bullets. Different seating depths.

Then there’s the program I use – QuickLoad – that computes internal ballistics.

So who to trust?

No one. That’s why you develop loads yourself using the load books as a guide. Cross-check one book to another. Cross check those to the program. See what agrees. What are outliers? Can you explain them?

I settled for a test range of 4.7 grains up to 5.4 grains seated at 1.230″ for the bullets I was using. This was well in the safe range for everything based on my checks. I loaded up 10 each in 0.1 grain increments. (Yes, I hand-weighed each one!)

Next up – testing!

These are the targets for the test. Each one has five rounds on it. I shot them with the gun resting on the bench in front of me while I was sitting. I wanted to remove me as much from the equation as possible. This was for accuracy now.

Look at the group sizes from the lightest load to the heaviest one. It starts big, gets smaller, then gets big again. The sweet spot is right around 5.1 grains of powder. A half-inch group at around 30′ isn’t too bad!

Why is that? I can make some educated guesses. On the low end you can have different powder burning characteristics that might lead to somewhat incomplete burning which would make for different velocities. On the high end you can get some resonances that you don’t want. The vertical stringing on the 4.7 target is a perfect example of differing velocities.

Here’s what QuickLoad predicts for my chosen load:

This will make power factor for IDPA and it seems to be the most accurate. Win!

BTW: I shortened the OAL by 5 thousandths to get better feeding. Of the 80 rounds tested (Ennie shot the other half) I had one feed issue so I’m shortening the cartridge a tad.