.45ACP actual case length compared to SAAMI specs

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Stimovsky

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I measured a hundred once-fired Geco empty cases length and got an average of 0.8910".
This makes the whole batch (but just one case) a tiny bit shorter than the SAAMI specification of 0.8980(-0.010) inches for headspace.
I would have expected a more significant part the batch to be inside the interval...

I'm not worried about anything, I'm just curious to know the reason why it is so.
 
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They can save a little brass and money if they make them all just a hair shorter:evil::)

Ok to be serious.
I would be curious what the lengths on some of them were before being fired.
Maybe shrunk a bit lengthwise and grew a bit diameter wise???
 
Dudedog said:
I would be curious what the lengths on some of them were before being fired.
Maybe shrunk a bit lengthwise and grew a bit diameter wise???
Click to expand...

I just measured 50 unfired rounds and got the exact same average for headspace. Your first hypothesis is probably the right one.
 
I mentioned the measurement I took as "headspace" because it is so designated on the SAAMI document I used.
 
cheygriz said:
Contrary to the long cherished notion that the .45 headspaces on the case mouth, most actually headspace on the extractor.
Click to expand...

Back in the day the idea was not to trim 45 ACP. If you measure a random sample of brass generally you find the average is shorter than specs. The reality of if is the cases generally run shorter. Tell you what, set you trimmer at the book length and commence to trim. You can do a bunch of cases in a short time.:)
 
I never measure .45 ACP cases, and never have any issues, although I do know one member here who trims his .45 ACP brass and says his pistol likes a certain length.
 
Rule3 said:
Very debatable
Click to expand...

If the article is correct then three of more generations of shooters have been given the wrong information. These misguided individuals were wrong thinking their handguns were accurate. It's the Myth Busters yet again! I'm taking thousands of rounds of too short 45 ACP brass to the scrap yard the day after Christmas. How could I be so blind!:eek::eek:
 
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Mowgli Terry said:
If the article is correct then three of more generations of shooters have been given the wrong information.
Click to expand...

It would not have been the first time...
...nor the last, I would imagine.

Shoulders, mouths, rims or extraction grooves. How it head spaces is not so important than that it does headspace.

Doing it the same every time leads to accuracy.
 
Walkalong said:
I worry about it this much. 0%. :)
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This is the exact amount of caring I'll allocate to .45ACP case length from now on.

May I now ask how much you guys would worry about crimping?
What would be your criteria? Based on what evidence should I decide whether "those rounds are not crimped enough" or "Dammit, those aren't crimped, they're strangled!"
 
Stimovsky said:
Based on what evidence should I decide whether "those rounds are not crimped enough" or "Dammit, those aren't crimped, they're strangled!"
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I use "do they chamber?". A little more crimp until they do, then stop. It won't matter of they're unstrangled if they won't chamber.

But yes, it can be overdone...
Causes leading.
 
Most brand new unfired .45 auto cases that I have measured for OAL are on the minimum. And that includes a lot of different brands.
 
I use an ancient C&H taper crimp die with Lyman T/C dies. I am blessed never to have any set back. Nor do I scrunch the brass. This crimping business is reloading 101. How much to you have to open a 45case to insert the heel of a lead bullet. The bullet seater should do the work of removing the crimp. Otherwise, generations of 45 ACP cases should not have chambered Right? The use of the separate taper crimp dies does make for a nice rounds.

Addendum: My press is an elderly Dillon 550.
 
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You are measuring the brass after resizing it aren't you? The die that you size with might be a hair wider than specs and therefore not squeezing/raising the length of the brass quite as much as specs. I have two dies and my Lee carbide die will end up with cases that are a couple thousands longer.YMMV

other than experimenting once I just load my 45 ACP brass no measuring involved.
 
I once had some that would not chamber.
All were in range pickup Hornady brass, the only .45s I have ever seen longer than spec. I wonder how they fired in the first place.

Us dinosaurs would load semiwadcutters into the lands for zero headSPACE.
 
My 1911's that I've looked at headspace on the case mouth. You'd need a pretty sloppy chamber, or very short brass, to headspace on the extractor.
 
45acp cases shorten with repeated reloading. They can be thrown away when it is determined that they are too short to head space in the chamber. Not something that I do.

They are head spacing on something other than the chamber when they shorten after repeated reloadings.
 
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