Load Development - .45 ACP in the Springfield Trophy Match

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.  :-P$0.082 - bullet$0.026 - primer$0.010 - powderI'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.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! :-D

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.