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Old February 5, 2012, 09:36 AM   #1
losacco
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Too much crimp, dangerous?

Hello everyone, I'm new to reloading and I just finished some 45ACP and 9mm. I probably didn't do enough research on tapper crimping and I'm worried that I have applied too much crimp. The case mouth edge is almost smooth against the bullet. Is this dangerous?

Patrick
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Old February 5, 2012, 09:53 AM   #2
griz
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Those two calibers headspace on the mouth of the case, so you could make the rounds unreliable and/or inaccurate. Shouldn't be dangerous though unless you squeezed them enough to distort the bullet.
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Old February 5, 2012, 10:40 AM   #3
Jim243
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Yes it is.


Jim

No crimps on 45 ACP & 9mm.
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Old February 5, 2012, 10:54 AM   #4
sigshepardo
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Those pistol rounds shouldn't be crimped. Crimping will increase chamber pressures. Too much crimp may result in wayyyyy too much pressure.
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Old February 5, 2012, 10:57 AM   #5
m&p45acp10+1
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You should be able to run your thumb nail down the bullet, and feel it lightly catch the case mouth. For adjusting your dies use a sized unprimed case screw the die down till you feel it contact the case mouth lower the case and screw down about an eighth of a turn. Then expand the case on your flaring die, and insert a bullet to make a dummy round. Seat a bullet and do the thumb nail test, and then the plunk in the barrel test. If it passes both then you are good to go.

Keep the dummy round in a labeled bag. I do this for every bullet I use. It helps later if I use something different, and then later go back to the other bullet I can use the dummy round to set up my die.

Note with semi auto rounds you are not realy crimping. Just removing the flare from the case. If the case mouth looks or feels like it is rolled in then it over crimped.
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Old February 5, 2012, 10:58 AM   #6
F. Guffey
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Too much crimp? I will assume you are crimping with a roll type or a taper type crimp, then then is the factory Lee crimp, after that is a long list of methods and techniques, then there is me using a carbide full length sizer die to remove the appearance of a case having swallowed a bullet, so, no there is no such thing as applying toooo much crimp, unless the reloader does not understand case expansion and ‘time as a factor’.

Then there is information available in books, books like Lee’s book on modern reloading, time wise, what is the difference between 200 psi and 600 psi, then there is the kinetic hammer, and Turkish 8mm ammo, there is so much crimp on the bullet it has a waist.

Then in the old days bullet were spiked.

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Old February 5, 2012, 11:02 AM   #7
p5200
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From what I've been reading on most forums, a lot of people have been using the LEE FCD. I know I was told to use it on my 9mm Luger rounds which, I use a very light crimp.
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Old February 5, 2012, 12:02 PM   #8
243winxb
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45acp

A slight taper is applied to the case mouth of the 45acp, .0002" Case mouth diameters are .473" or smaller. The case wall thickness makes a difference between brands. The mouth could be as small as .469" from what i have seen. SAAMI Drawing/measurements > http://www.saami.org/PubResources/CC...0Automatic.pdf
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Old February 5, 2012, 08:41 PM   #9
wncchester
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'Bout all I've ever "crimped" for any autoloader (.45/9mm) cartridge was enough to remove the mouth flare so they will chamber reliabily, that's all they need.
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Old February 5, 2012, 09:16 PM   #10
steve4102
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Quote:
Those pistol rounds shouldn't be crimped. Crimping will increase chamber pressures. Too much crimp may result in wayyyyy too much pressure.
This is not an accurate statement.
Yes, you need to crimp your 45 ACP ammo. You taper crimp the case mouth just enough to remove the flare that was applied with the expander die. A taper crimp is not used to secure the bullet, only to remove the flare plus maybe a thou or two. Failure to remove the flare will cause feeding issues in most semi-auto pistols.
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Old February 6, 2012, 10:22 AM   #11
Jim243
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Quote:
The case mouth edge is almost smooth against the bullet. Is this dangerous?
OK, it appears that this has to be explained.

Take you barrel out of your pistol and look down the barrel from the chamber sided. You will see that the chamber is slightly wider than the barrel and that there is a ridge in the barrel. That is what your case "indexes" on (stops the foward movement of the case). If you apply too munch crimp on the case, it does not stop where it should and is pushed into this ridge. This compresses the bullet in the case and does not allow for it to release from the case. (jammed into the case and barrel).

When you fire off that round, the bullet will be jammed and all the pressure has to go somewheres, where - back to your slide, mag well and frame. The gun will come apart at the mag well, grips and the slide will be slammed back at you, maybe in your face if the rails have been moved apart enough.

Learn the difference between removing the flare from your powder through die and a "CRIMP".

DO NOT CRIMP - PISTOL CARTRAGES, revolver cartrages yes, pistol NO.

Stay safe.
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Old February 6, 2012, 11:03 AM   #12
serf 'rett
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^ What Jim said.

Plus, I've heard of overcrimping causing the bullet to actually become "looser" in the case due to case deformation. This could lead to bullet setback on feeding; with the result being an over pressure round(s).
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Old February 6, 2012, 11:14 AM   #13
IllinoisCoyoteHunter
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Quote:
DO NOT CRIMP - PISTOL CARTRAGES, revolver cartrages yes, pistol NO.
A revolver is a type of pistol. This should read "Do Not crimp semiautomatic pistol cartridges, but crimp revolver cartridges"

I know I am nitpicking but the use of proper terminology can lead to better understanding for everyone!

This is all according to the NRA....
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Old February 6, 2012, 02:01 PM   #14
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Quote:
DO NOT CRIMP - PISTOL CARTRAGES, revolver cartrages yes, pistol NO.
I disagree with this statement. It seems to me you are implicitly implying "do not roll crimp cartridges for semi-autos", which is correct. But that's an incomplete statement. It is absolutely correct to taper crimp (ie, the Lee FCD) cartridges for semi-autos. Taper crimps lightly squeeze the mouth to both remove flare and add a slight amount of neck tension.


I think it is a bad idea to be playing semantic games about the differences between "removing the flare" and "crimping" as well.
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Old February 6, 2012, 02:20 PM   #15
F. Guffey
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I am the fan of bullet hold, I want all the bullet hold I can get, I crimp everything I shoot in pistols. I have TC dies, I have seater/crimp dies that also applies a TC, for other cases I have roll crimp dies that double as seater dies.

I am the fan of crimping, then for those pistols that like new, store bought, factory, over the counter ammo I have the carbide full length sizer die, it works wonders on cases that look like they swallowed a bullet.

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Old February 6, 2012, 03:15 PM   #16
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I never knew crimping (taper or otherwise) could get so contentious.

OP: Perhaps a picture of the cartridges in question could help us give clearer guidance. Then again, perhaps not
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Old February 6, 2012, 04:51 PM   #17
Tim R
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For auto loader pisatols I take the crimp out with a taper crimp. I seat the bullet abd then come back to remove the bell.

For revolver ammo, I crimp lightly. The case mouth bends into the crimp grove but not a lot.

If brass needs a crimp to hod the ullet, then your brass is likely to be worn out.
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Old February 6, 2012, 05:45 PM   #18
243winxb
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We will know soon in this thread running now. > http://thefiringline.com/forums/showthread.php?t=478042
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Old February 6, 2012, 06:21 PM   #19
Ole 5 hole group
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you use a taper crimp for the 45 ACP - like some have mentioned it's to take out the flare/bell and add a bit of case tension to the bullet. Your bullets should be either 0.451 or 0.452 in diameter. It's helpful to seat and taper crimp in seperate operations, so back off your seating die a little. Measure the case mouth after seating the bullet - will probably measure 0.472 to 0.475 - then set your taper crimp die so your finished loaded round measures 0.469 to 0.470 at the case mouth (that's measuring at the very end of the case where you see the bullet), not a 1/16" below the bullet. Some go a little heavier at 0.468, which is fine, while others like 0.471".

You might notice different powders like more or less case tension. I find VV350 with 230 grain likes 0.469 while VV310/VV320 will shoot anything well (0.468 to 0.471) in lighter bullets (185 or 200).

Applying to much crimp may effect your accuracy but I seriously doubt you could make that cartridge unsafe in a modern firearm.
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Old February 6, 2012, 11:01 PM   #20
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Of course, how overcrimped they are is the question. can you actualy see the case digging into the bullet? Like was asked in post #5, can you run your thumbnail down the case and feel the bump where it meets the case? If so then you are probably fine. mine look pretty smooth from case to bullet. Do you have a pair of calipers? I am pretty sure mine are crimped right, and when I slide the caliper head down the bullet till it meats the case and measure, I measure .005-.010"

From what I have read, most likley you will be fine as long as your extractor is in good shape. Even if you put too much crimp on it, the extractor will hold the case in the right place, basicaly the same thing as trimming the brass too short.... If the extractor wont hold the case up against the breechface then I would worry....
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Old February 6, 2012, 11:01 PM   #21
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Losacco,

The potential pressure danger Jim243 warned about is real. You really do need to keep the case mouth from getting into the throat of the barrel and interfering with bullet release. But that is the only absolute rule at work here, and there is more than one way to skin that cat.

One is simply to make the cartridges as John Browning intended. That means a crimp may be applied to the case mouth only to the point the outside diameter of the mouth is no smaller than the minimum dimension specification for the loaded cartridge. With .45 ACP this is 0.467" at the mouth, and with 9 mm it is 0.373" at the mouth.

You won't be able to taper crimp a jacketed bullet much without excessive pressure, and you don't need to, as copper gilding metal and brass have plenty of friction between them to keep the bullet in place. But with lead bullets, because of their softness and lubrication, they can sometimes be set back in the case during feeding, which can also create dangerous pressure. Putting a slight crimp in the lead (we're just talking thousandths here) creates a very small step that can help prevent that setback. With jacketed bullets I can identify no advantage to a crimp beyond removing the expander flare, but with lead I think that small bite has a small safety benefit. This is especially true using cases that have been reloaded many times and that have begun to become springy and no longer resize down as much in diameter to grip the bullet as well as they once did.

Many modern reloaders will be dismayed to hear that most all the old time top bull's eye match shooters used to roll crimp a good bite into .45 ACP lead bullets. They claimed it gave them best accuracy because the resulting higher start pressure makes the powder ignite and burn more consistently. You can go look up pictures of their loaded rounds in old publications and see it clearly, and where they've been interviewed on their loading technique they describe doing just that. The trick is doing it without letting the case mouth get into the throat of the barrel where Jim's pressure warnings apply, and at least two things can assure that: headspacing on the extractor hook or headspacing on the bullet.

Mr. Browning's original design intended rimless pistol cartridges to be headspaced (stopped from going further forward into the chamber¹) by the mouth of the case stopping against the shoulder in the chamber where the end if the case is supposed to be (the ridge Jim243 described). Often, this does not actually happen, though. Often chamber tolerances are loose enough that the case is actually stopped from going further forward by the rim contacting the extractor hook before the case mouth reaches that shoulder. This is called headspacing on the extractor hook. I once saw an estimate that up to 70% of new 1911's do this. I don't know if that's accurate, but it is the most common source of breakage of cheap or improperly heat treated extractors. If you have a gun that is doing this (and it has a good quality extractor), then no amount of crimping you do to the cartridge will put you in danger of the case mouth going into the throat.

Checking for headspacing on the extractor can be done several ways. One way is to drop a case that is fully resized and maximum length (0.898" for .45 Auto, and 0.754" for 9 mm Luger) into your barrel and measure how much distance is left to the back end of the barrel (if your case is shorter than maximum, just subtract the difference from your measurement; we want the measurement to cover worst case, and doing that will get it there). Next, add the minimum rim thickness spec for your cartridge to that result (0.039" for .45 Auto, and 0.040" for 9 mm). Write the final number down. Next, measure the distance from the breech face of your slide to the forward inside edge of the extractor hook. If the result is smaller than the first number you calculated, your gun is headspacing on the extractor hook.

That is a good thing to know about your gun, but because of the potential for extractor breakage, it's not the thing I depend on. Also, though it is functional with jacketed bullets and a good grade extractor, headspacing on the extractor interferes with accuracy with lead bullets because it lets them fire at a slight angle so the chamber shoulder scrapes lead off them and unbalances them. So I depend on headspacing lead loads on the bullet, which keeps the case head near enough to the breech face to prevent the leading edge of the rim from reaching the extractor hook before the bullet is already properly started into the throat (no angle or scraping).

Below is an illustration of bullets in different positions in a barrel that is being used as the gauge. Drop an empty case into the chamber of your barrel and note the distance to the back of the barrel that is left. That's where that case would be if it were headspacing on the case mouth and if the extractor hook didn't stop it first. Adjust your bullet seating depth out until the bullet stops it first. Bit if you simply seat the bullet out far enough that when you drop a loaded round in the barrel the case head is flush with the back of the barrel, as shown in the third position from the left, you will be headspcing on the bullet or at least getting the bullet properly started into the throat.

Headspacing on lead bullets maximizes accuracy as well as reducing leading by stopping shaving on the chamber shoulder. I've had several people on this board and others verify this result. In my own wad guns with light loads, the improvement in group size has been as much as 40%, so it's not a trivial improvement. The only hitch is if your chamber is so long the bullets seated this way won't fit in your magazines or won't feed properly. It normally takes a pretty long chamber to make that happen, but you should test. The standard 200 grain semi-wadcutter designs don't normally cause a problem with it.




¹This is not a correct definition of headspace, but is the practical purpose it serves. Back when the head of a cartridge was defined by its rim (still true in modern rimfire cartridges) and most cases were straight and many bullets were heeled, the amount of room in the recess at the back end of the chamber for the rim to fit into was the only thing that stopped the cartridge going too far into the chamber. Since the rim was the head, this rim room came to be called headspace. When later rimless and belted cartridges came along which were limited in their forward entry into the chamber by their shoulder, belt, or case mouth instead of some part of the case head, the old terminology nonetheless was carried over. Thus we now declare headspace by what the case stops against. The case is said to headspace on the rim, belt, shoulder, or mouth, depending on the design.
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Old February 6, 2012, 11:10 PM   #22
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One other thing that has not been brought up. A slight taper crimp will help eliminate bullet set-back when the round hits the feed ramp and chambered. I taper crimp all my 9mm and 45acp.
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Old February 7, 2012, 12:22 AM   #23
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Uncle Nick, that's an excellent post.

And excellent visual aides.

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Old February 7, 2012, 02:30 AM   #24
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There are a couple of scenarios not mentioned so far. I'm referring to shooting a 45 ACP chambered revolver. My old Ruger Convertible had a cylinder with a rim in it that a round's case mouth head spaced on. There is no extractor on such a gun, so heavy roll crimps could possibly cause a problem.

The other scenario is a revolver designed to use moon clips locked into the extraction grooves. Of course in that case there is no extractor either, but the round is headspaced against the moon clip. (or two half-moon clips). In that case it doesn't matter if it is roll crimped. In fact such a roll crimp might even be preferred for the reason Uncle Nick already mentioned.
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Old February 7, 2012, 12:57 PM   #25
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UncleNick is the shiznit!
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