How short is too short?

C

cdoc42

New member
I'm loading a few 9mm and the case size should be between 0.754 and 0.744 inches, with the median being 0.749. So that range should suffice to meet the requirement for headspace.

A few of my cases were less than 0.744, discovered when I began to flare a bunch of resized cases, and loading these often resulted in bulges, which would not allow the cartridge to go into battery.

So that, of course, should answer my question. But- if I take care in making certain that the bullet is as perpendicular to the case as possible as I seat it, that cartridge has no bulge and will go into battery.

I researched this and I found the warning that a case that is short of headspace poses a problem where gases can escape, tearing or rupturing the case, allowing gas flow backward rather than forward, damaging the gun to the possible point of rupture. The only thing missing in this recommendation was how critical the size of the case might be. How short is too short?
 
Beats me. I have never measured a 9mm case. A taper crimp takes care of such variation as turns up. I gauge 100% and the few that fail the gauge will generally plunk and shoot. No scary blowback.

I once came across some 9 Makarov that ran through the Dillon unnoticed until the gauge. I finally shot a few which fed, fired, and functioned normally. So I don’t worry about case length.
 
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I never measure 9mm cases either.
RANGE BRASS
Clean
Sort out Blazer/Winchester/Federal/AAC Brass
Size with an RCBS Carbide Die
Swage Primer Pockets on the brass not sorted out
Load on my 550 Dillon with Dillon Dies.
Good plan to plunk test

Bob R
 
For years I used a Lee FCD to deal with case bulges and it worked. Since NOE has come out with their Powder Through Expanders I no longer get bulged cases using these with the Lee Pro Disc powder measure. I see Lee has also come out with their own version of these expanders but since I converted all of my pistol dies to the NOE version I’ve had no reason to try them.
 
A few of my cases were less than 0.744, discovered when I began
to flare a bunch of resized cases, and loading these often resulted in bulges,
Click to expand...
I'm not sure why seating a bullet to the same OAL in a slightly short case would result in a bulge.
Can you elaborate?
 
It sounds like the bullets are tipping to the side and being seated cocked at a slight angle in the case's mouth. This does put a bulge in cases that shows up on the side opposite to the direction the cocked bullet is pointing. The solution has long been to use a Lyman M-die type of expander that puts a short, straight, expanded cylindrical length in the case mouth that is just over bullet diameter below the bell of the flare. This straight portion lets you set the bullet into the case, pointing straight up and down, and when a straight up and down bullet is seated, it stays straight, and any slight bulge it makes is then uniform all around and not too large to chamber. The slight bulge from straight bullets is due to the straight sides of a case that has been resized by a carbide ring rather than having a die with the designed case taper, as steel dies do.

The patent on the Lyman M style expander has long since expired, so a number of companies have copied it, like Redding, Hornady, and NOE. You can, however, also buy a powder-through die from Lyman in a kit called the Lyman Multi-Expander that comes with the hollow expanders in this profile for all common pistol calibers, from .32 to .45.

Incidentally, folks not wanting to invest in an expensive bullet alignment-straightening seater (e.g., the Redding Competition Seating Die) have obtained excellent results by using a Lyman M-die for rifle calibers with their jacketed bullets and a more conventional seating die like the RCBS standard seater or the Lee dead-length seater. They adjust the M-die to get the short straight step in the case mouth but not far enough to get the flare, and this lets them set their bullets straight up for seating and get 80% or so of the effect of the expensive seating dies; enough to tighten groups in some rifles. The little bit of extra diameter at the case mouth can then either be ironed out with a taper crimp die, a Lee Collet Die or even a light touch of the roll crimp shoulder in a standard seating die, or, if you don't have a tight match chamber neck, simply leaving the extra couple of thousandths of diameter alone can help center the bullet in the chamber neck a little.
 
I bought an alleged M type Dillon "powder funnel" but it did not have enough step to get along without a flare like my real Lyman Ms. I am reluctant to blow another $44 to try a different brand.
My Hornady sliding sleeve seating die aligns bullets pretty well.
 
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Once again, Unclenick provides a detailed answer to the bulged issue. But I believe I also answered it in a less detailed way in my original post: " if I take care in making certain that the bullet is as perpendicular to the case as possible as I seat it, that cartridge has no bulge and will go into battery." I'll add that the shorter case has less flare, making bullet tipping more likely.

I appreciate all the replies and I agree that, up to this point, I have never bothered to measure any pistol or revolver cases. It's just that in this instance, I happened to do so, and the research revealed the warning resulting in the question I presented:

"I researched this and I found the warning that a case that is short of headspace poses a problem where gases can escape, tearing or rupturing the case, allowing gas flow backward rather than forward, damaging the gun to the possible point of rupture. The only thing missing in this recommendation was how critical the size of the case might be. How short is too short?"
 
Did that research specify what type of case? You can get into trouble with "headspace" in a bottleneck rifle cartridge but there seems little evidence of problems in straight pistol cases.

As I said, Makarov brass gave normal operation in a 9mm P, no doubt it was feeding properly and coming up under the extractor to hold the round against the firing pin.

A much earlier discussion of .45 ACP case length (cylindrical cases tend to shorten with use, not stretch like bottleneck) brought about a test of .45 GAP in an ACP gun. Results were the same, the rounds fired with no drama.
 
Flare more; or use bevel-base bullets or bullets with a nice radius on the bottom corner. Then you don't need to flare at all.


Most semi-auto handgun cartridges get shorter over time, and never need to be trimmed.
How short is too short?
I don't know. I have never had a problem. If it looks like usable brass, I use it without measuring. (And if it doesn't look usable or causes a problem, it gets recycled. I *might* measure if it looks like .380 Auto fired in a 9x18 Mak chamber - but I'll probably just toss it in the recycling bin instead.)

How short is too short will be dependent upon the handgun in which it is being fired, certainly. Tolerance stacking is going to be the primary concern, rather than an exact case length.
SAAMI allows chambers to range from .754" to .776"; and cases to range from .744" to .754". Striker/firing pin protrusion can come into play.
A minimum (or shorter) case length is going to be more likely to light strike or blow a primer in a maximum chamber, than in a shorter chamber. Each pistol is going to be a little different.

Some people suggest seating bullets to touch the lands to "correct" headspace in long chambers. But that has its own set of problems and risks.
 
Jim Watson said:
I bought an alleged M type Dillon "powder funnel" but it did not have enough step to get along without a flare like my real Lyman Ms. I am reluctant to blow another $44 to try a different brand.
My Hornady sliding sleeve seating die aligns bullets pretty well.
Click to expand...

I am curious: was this one of the HTC funnels sold by Uniquetek? Was your Dillon press the Square Deal B? You do need to set the funnel low enough that the case mouth goes clear past the straight step section to the wider portion above the step that adds the normal flare. Uniquetek has a note on their sight that the HTC funnel is too short for the adjustment range of the die on the SDB, so if the SDB is what you have, they have a separate spacer kit to get that working properly.


Cdoc42,

The gas leakage issue varies with chamber and pressure. If the peak pressure is high enough and the powder burns quickly enough, by the time the bullet is released by the case, the case should be expanded to seal against the reverse flow of gases. A few thousandths short of the SAAMI minimum should not make any difference to this.

The real issue with short cases is just headspacing. When I noticed my 45 ACP cases shortening with repeated reloading and getting well below the SAAMI minimum, I realized they would eventually get short enough to cause my cases to be headspacing on the extractor hook rather than the step in the chamber that is intended for the purpose. This is common, and a lot of 1911s used to be so loose coming out of the factory that they headspace on the extractor hook right out of the box. The aftermarket in tough steel extractor hooks was born from this situation. My solution was to seat my bullets long enough to stop in the throat of the bore before the rim reached the extractor hook when chambered, then work my loads back up to match the new dimensions. Works fine and shrank my sandbagged groups by 40% with swaged and cast bullets (never affected jacketed bullet accuracy, which was good either way).
 
I am curious: was this one of the HTC funnels sold by Uniquetek? Was your Dillon press the Square Deal B? You do need to set the funnel low enough that the case mouth goes clear past the straight step section to the wider portion above the step that adds the normal flare.
Click to expand...

No, it was the MR/DAA part.
No, it was in a 550.
The step was barely perceptible and even with a flare, the bullet did not go down into the supposedly expanded section.

I was going to discuss with Photo Escape who makes the current Uniquetek part but their www reply form did not want to play. Maybe I did not pass their bot blocker test.
 
"I researched this and I found the warning that a case that is short of headspace poses a problem where gases can escape, tearing or rupturing the case, allowing gas flow backward rather than forward, damaging the gun to the possible point of rupture. The only thing missing in this recommendation was how critical the size of the case might be. How short is too short?"
Click to expand...

Who gave this warning, and where did you find it???

Because it doesn't make sense to me.

It might, possibly apply to a certain specific cartridge & firearm combination, but I can't think of any example, and, as a general rule, it just doesn't work.

Since you're loading 9mm Luger, lets look at that (and other cases that headspace on the case mouth), first.

Look at the gun(s) you are using. The headspace shoulder (ledge) in the barrel at the front of the chamber is (or should be) cut to allow a case of max spec length to chamber. .754" for the 9mm Luger.

This means that every case shorter than that going to fit. How short is too short?? In practical terms, it depends on the gun. There are many gun designs that, while made to headspace the case on the chamber ledge, actually "headspace" the case on the extractor claw when the case is not long enough to reach the chamber ledge.

As long as the case is held close enough to the breech for the firing pin to strike the primer, the case will fire. Pressure then expands the case to the limits available, the steel of the chamber walls, where it seals keeping the gas from going "backwards".

The sealing of the brass against the chamber walls is a function of diameter, NOT length.

It is possible to have cases too short for the loaded round to feed properly. It is possible that a too short case may go too deeply into the chamber to allow firing, IF the gun design allows it to. It is a fact that "too short" cases will affect reloading when your dies are properly set for longer cases. How much of an effect depends on the actual difference in tolerances in your specific situation.

"Too short" means extra care needs to be taken when reloading those cases. Different die adjustments may be needed. Doesn't mean you can't make functional ammo, it just means you have to be aware of the difference and make allowances for that.

NO one is going to give you a "too short" number, as it can be different for different guns. I'm referring to "too short to work", not "too short to be out of spec". Some guns will run ok with ammo shorter than min spec. Some won't.

As written, I find the warning you ran across to be Chicken Little BS, in that it assigns case failure (and escaping gas as a result) to case LENGTH, and in my experience, that is simply NOT the cause.
 
44AMP, I found it on Wikipedia under "headspace"- here is the paragraph that caused the concern:

"When the headspace is larger than the cartridge case, there is front-to-back cartridge wiggle room when the breech of the gun is closed. This extra space is called head clearance. Many, including some major manufacturers, confuse head clearance with headspace in their literature. This commonplace error is explained in the glossary of firearms terms maintained by the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI), which is the ASTM standards organization for the U.S. firearms and ammunition industry. Excessive head clearance is undesirable for several reasons. It can allow a cartridge to slide forward beyond the distance within which the firing pin has the ability to adequately indent the primer for reliable ignition (though extractor hooks may act as the replacement headspace determinant in this situation). In chamber designs that don't fully support the case head, excess headspace can allow a case to expand excessively, which can thin or crack open the brass. Thus, the cartridge can rupture rearward, which releases hot gases under high pressure that can damage the firearm and injure or even kill the shooter or bystanders.[1]

I recognize that I may have "over-read" that, ignoring the chamber design probably having more to do with the warning than the length of the brass case.
 
That quote section is only talking about unsupported chambers (feed ramp). This known as Glock bulge or smiles (nothing to smile about) depending how bad. Nothing to do with case length.
 
The Glock "ka-boom" was due to the unsupported rear of the chamber, which was done to improve the feed reliability of the gun. This did work, but resulted in the brass case swelling into the relief cut area, and when the distance was more than the case could handle, it would rupture. (aka Ka-boom!) this usually didn't happen with 9mm rounds but did happen enough with .40s and even some .45s to become legendary.

This result did happen with "full length" ammo, it wasn't just "too short" cases, and actually case length had nothing to do with it.

A case with "perfect" headspace can rupture in an oversize diameter chamber, and that is what the Glock unsupported chambers are. OVERSIZE in diameter at the point of the feed ramp area.

The Wiki report is correct about the unsupported chamber allowing the case to rupture. They are incorrect about the case LENGTH being the reason.
 
It doesn't say case length is the reason, but that excess headspace is. I authored that revision of Wikipedia's definition of headspace, which was poorly stated originally. What I had in mind with the red-highlighted portion of the text is rimless high-power rifle cartridges that have an unsupported gap at the bottom of the closed chamber. In that instance, excess head space results in greater pressure ring thinning than is normal, which can lead to a brass blowout, especially in cases that have been reloaded without performing the paperclip test. You will note the numbered reference [1] at the end. This refers to several pages on the subject of headspace by Gen. Julian Hatcher in the Wm. C. Davis compiled NRA book Handloading, which is where the information originates. Page 69 has the description of case ruptures caused by excess headspace in paragraphs 11 through 12.

Obviously, the Glock bulge and the "pregnant" cases ejected from a 1911 with an unsupported chamber (rather than the later integral ramp chambers that surround the case more completely) are also potential candidates for a rupture. Sizing dies, bulge busters, and the like will remove those bulges, but I don't have a good sense of how many times you can do that for cases firing full-power loads before over-working the brass.

The confusion here suggests I need to re-edit the text in red.
 
Thanks again to everyone for clarifying this question. Is this a safe assumption?: If a 9mm fired, resized case measures 0.738" with the SAAMI recommendation being 0.744-0.754 there is no safety concern if the cartridge goes into battery and fires normally.
My understanding is that the extractor hooks prevented forward movement in the chamber even though the headspace was excessive. If the mouth area of the case is black, is that from gas blowback before the bullet entered and engaged the leader, but the case would expand to prevent further blowback as described by the Wiki article?
In addition, is it correct to say the short case might have an insufficient flare, interfering with proper bullet seating, causing a bulge large enough to prevent battery completion?
 
I never measure pistol case lengths but I do Shockbottle every round.


rjHG.jpeg
 
Cdoc42,

You've basically got it right. The case expands under pressure, but that starts happening while the bullet is still in the case, so it doesn't expand near the mouth until the bullet is out of the way. So you get a seal behind the mouth area first, and then the brass has a rolling expansion along the sides of the bullet as it starts to move, and when it finally expands at the mouth, the pressure equalizes before the mouth fully seals against the chamber, so it is normal to see some color immediately behind the case mouth. You often see that even on high-power rifle brass firing at higher pressures than a full 9 mm load. Don't worry about it unless it goes all the way along the sides of the brass to the head.

The flare can be insufficient if the die doing the flaring is set up to flare a SAAMI-spec case. If your cases are all short, set the die up to flare cases of the length you have, and then it won't be insufficient anymore.
 
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