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Old February 1, 2011, 06:48 PM   #1
Praxus
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Crimping 9mm luger

I am fairly new to reloading, having reloaded less than 1,000 rounds of mostly 9mm luger. I was reading some posts on here last night regarding crimping pistol rounds. Someone made the statement that to check the amount of crimp on the bullet I should push the bullet against the work bench and see if it pushed the bullet further into the case. Well I did and the bullet went all the way to the powder with very little applied force. Obviously I am not putting enough crimp on the bullet, more than likely I am crimping just enough to take out the bell from the sizing die. I am using Lee dies and I know that in order to increase the amount of crimp being applied that I need to rotate the seating die clockwise 1/8 of a turn at a time until the desired amount of crimp is achieved.

My question is: How do I know how much crimp is too much and how much is enough, are there any visual cues that will help me know when I'm putting too much or too little crimp on the bullet. Is there any way to measure and quantify the amount of crimp that is being applied to the bullet.

I understand that since the 9mm is not a cannelured bullet that excessive crimp will more than likely affect the performance of the bullet and the pressure in the cartridge. I would like to be able to quantify the amount of crimp being applied so that I can improve the consistency and accuracy of my reloads. Any help that you can offer would be greatly appreciated.
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Old February 1, 2011, 06:58 PM   #2
chris in va
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Just a light taper crimp is needed for the 9mm, enough to prevent the setback as you discovered. Turn the die in a little at a time until you start noticing the case mouth is slightly rounded in toward the bullet. Very slightly.

My CZ however refuses to run unless I put it through the Lee FCD and give it enough taper crimp to make the case mouth flush with the round. Otherwise it gets hung up when feeding.
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Old February 1, 2011, 11:18 PM   #3
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Thanks Chris, I have noticed a few posts where people have specified a crimp of 0.431 for example. How is this measured? What is the criteria for comparison? I assume this is a measurement taken with a caliper, but I'm not sure how to arrive at this value to quantify the amount of crimp being applied to the bullet.
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Old February 1, 2011, 11:33 PM   #4
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I barely take the flare out.

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Old February 1, 2011, 11:42 PM   #5
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The thing to read here is “taper crimp” as opposed to roll crimp. 9mm’s head space on the case mouth, rolled crimps cause problems on 9mm’s. A taper crimp is just swaging the case to the bullet. The amount of swage is determined by measuring the diameter of the case at the very case mouth with bullet installed. A taper crimp die is used for this operation and a dial caliper is used to measure the results. The amount of taper crimp varies with who or where you get your information.
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Old February 2, 2011, 02:48 AM   #6
chris in va
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Quote:
I have noticed a few posts where people have specified a crimp of 0.431 for example.
Skip all that. Taper crimp it a bit, drop it in your barrel to make sure it chambers fully, good to go.
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Old February 2, 2011, 05:49 AM   #7
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Ok, thanks for all the good advice guys. Here's what I did: I loaded approximately 200 rounds tonight, I adjusted the bullet seating die clockwise about 1/4 turn and then set the bullet seating depth using a round that I knew was 1.125" COL. After I loaded a round i pushed the bullet against the bench using the force applied by my thumb. Since the bullet did not set back I backed the seating die out a little until i found that I could set the bullet back by applying thumb pressure. At that point I turned the seating die clockwise slightly to ensure that it was applying a sufficient crimp to the case, while at the same time not overdoing it. Does this sound about right? Thanks again for all the help fellas. I hope this will help improve the accuracy and consistency of my reloads. I also noticed that when I last shot a batch of my reloads that I was getting a noticeable amount of powder buildup in the barrel. Hopefully by adjusting the crimp this will be minimized as well.
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Old February 2, 2011, 07:57 AM   #8
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Interesting info guys. Just out of curiosity, what would happen if one attempted to fire a round that had too much crip on it?
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Old February 2, 2011, 09:24 AM   #9
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I am not sure that setting the bullets back by using a bench or your thumb is what anyone is after. Just load your bullets fire your gun once and then take your callipers and measure the remaining bullets and see if you have any set back. If you do have some set back (C.O.L. less than when you first started) then crimp a little more. I run my taper crimp die down to the case then give it a 1/4 turn more and it seem to work fine. If you want to measure the diameter of the the case mouth after crimping then put your callipers on the case mouth and measure there. I believe mine measures around .377,.376, my cases have not been trimmed to the same length so my crimp varies.

The only reason that I crimp is that a while back I was haveing a little trouble getting my bullets to feed so I started to crimp and the feed problem went away. Ok, the real reason is that I loaded for 9mm and S&W 40 and had no real problems until one day I started to load for a 38 special and it took me 3 weeks to figure out that I had to crimp my rounds to take out the case bell in order for the bullet to fit into the cylinder of my revolver. (Guys on this forum helped my figure it out) After that I started taper crimping everything. Now let just say here that the 38 special rounds I load (So far) are not cannelure d and that the 38 special round is something completely different than what we are talking about here.

Mostly if you don't bell the case mouth more than what is necessary then you should not need to taper crimp your loads. I never had a problem with set back in my 9mm, S&W 40 before I started to crimp. So the best thing I can tell you is to not over crimp and use a taper crimp on the 9mm but I cannot tell you how much is to much. As a rule of thumb when first starting out in reloading just puck up a factory round and start from there. Just measure a store bought round and see what the measurement is at the mouth of the case and start there.

Good luck'
Mike
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Old February 2, 2011, 11:41 AM   #10
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You can get pretty anal when dealing with taper crimping, I know, I did. Back in my bullseye shooting days every case was trimmed to the same length and every case had the same amount of taper crimp, same bullet weight, same charge, everything.

Of course this made for excellent target loads, but for most folks all this is just a waste of time. Just taper crimp till the bullet is secure in the case and doesn’t move during recoil and you’re OK. Don’t over taper crimp, it will affect head spacing just as roll crimping can do. A little common sense and some trial and error you’ll be OK. It ain’t rocket science.

If you want to play with taper crimp numbers check the case mouth specs on factory ammo or refer to the case mouth measurements in your reloading manuals.
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Old February 2, 2011, 11:45 AM   #11
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Well said Hog Buster...
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Old February 2, 2011, 11:52 AM   #12
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PaseMkr

It can cause light primer strikes causing misfires, over pressure, if driven too far into the barrel when fired, extraction and/or ejection problems along with generally poor performance.
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Old February 2, 2011, 12:04 PM   #13
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Thanks Mike

I hate to see new reloaders get wrapped up in dealing with angstrom units when it’s not necessary........
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Old February 2, 2011, 06:22 PM   #14
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Wow, thanks for all the great advice guys. I measured a few of the rounds that I loaded last night and most of the case mouths were in the range of .375-.377. This appears to be in line with what the consensus of this group seems to be. I didn't trim the cases so I expected there to be some variation in the crimp. I'm also using the seating die to crimp the cases rather than the Lee factory crimp die, which I don't have. Thanks again for all your help. As soon as we dig ourselves out of the snow here in the midwest I'm gonna try to get to the range so I can test these out.
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Old February 2, 2011, 06:56 PM   #15
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One thing you will realize is that all 9mm brass is not the same there is a lot of variation in case length and thickness all which will have some affect on your taper crimp setting.

In reloading straight wall cases that headspace on the case mouth we use a “taper crimp” die. However this die doesn’t really “crimp” anything. It’s sole purpose in life is to remove the flair on the mouth of the casing so the round feeds and headspaces correctly.

A properly adjusted taper crimp die may or may not increase bullet tension by as much as 10%. Screw that die down further and the casing starts to buckle releasing it’s grip of the bullet.

Bullet tension is determined by:
1. The resizing die.
2. The expander plug. (Bell mouth die)
3. Case wall thickness.
4. Bullet diameter.

The best way to properly set up your taper crimp die is first resize a casing and measure the mouth diameter with a set of calipers. Now take that empty casing and run it through the crimp die and measure again. The two measurements should be the same, or up to .002 smaller,less is more when it comes to taper crimping.
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Old February 2, 2011, 09:17 PM   #16
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Good deal Praxus, get out there and burn some holes in the snow. Down here in the sunny south the snow is coming down in buckets....... We call it rain........
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Old February 4, 2011, 02:21 PM   #17
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Quote:
The best way to properly set up your taper crimp die is first resize a casing and measure the mouth diameter with a set of calipers. Now take that empty casing and run it through the crimp die and measure again. The two measurements should be the same, or up to .002 smaller,less is more when it comes to taper crimping.
res45 - Excellent technique for setting the taper crimp die. Thanks.
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Old February 4, 2011, 07:45 PM   #18
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"Just out of curiosity, what would happen if one attempted to fire a round that had too much crip on it?"

Guess too much crimp would pinch the nose of the bullet off; short of that, not much. All we need to understand about crimping a 9mm is, "not much."

9mm bullets are light and the recoil is quite modest. Pulling bullets isn't a problem if for no other reason than the magazine's front wall prevents it. Nor is set back in the magazine likely to occur, the recoil is far too little for that (it IS a puny round!). So, all we really need is to remove the case mouth flare completely to insure smooth chambering.
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Old February 5, 2011, 01:22 AM   #19
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Wncchester. I take it you don't shoot 9mm major
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Old December 20, 2012, 07:35 AM   #20
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Great Thread

Hello,
I recently purchased a Dillon XL 650 and am starting to reload 9mm. The setup was used and came with 9mm 40sw and 45acp dies. The previous owner did not use crimping dies on the 9mm setup but had them for the other two calibers.
I loaded 25rds last night using 4.3g of Bullseye, Winchester small pistol primers and 124 fmj round nose projectiles. I am off to the range today to see how they shoot. I tried dropping the loaded rounds into my 92A1 barrel and at first some were a little tight. I lowered my seating die very slightly and backed off the seating height the same amount. This seemed to help after I re-seated all my reloads.
I will let you know how I make out.

Thanks for the information.
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Old December 20, 2012, 09:59 AM   #21
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Quote:
Originally Posted by 1SOW View Post
Wncchester. I take it you don't shoot 9mm major
I was thinking the same thing. The round I am currently using for 9mm HD is a Buffalo Bore 115gr pushing 1400fps and 400ft.lbs. Not exactly "puny".

Of course, my EDCs are .380s, so small calibers have never been a problem for me.

There was a time when 5.56 was considered puny.
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Old December 20, 2012, 07:21 PM   #22
Gerry
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I don't know why folks are advocating crimp to prevent set back. Set back happens because you don't have enough tension between the bullet and your case. In a straight walled cartridge like 9mm, this tension is achieved by pressing in a bullet that is slightly too big for the case. What holds your bullet is only this tension of the case neck against the sides of the bullet itself. The amount of force to press the bullet in further would continue to deform the case walls by stretching it. This takes a lot of force! Hence the press to get the bullet into the case in the first place.

A taper crimp overdone can undo this tension. The reason is that copper springs back more than lead does (even using jacketed bullets). You squeeze the bullet a bit inside the case, and the case later springs back a microscopic amount while the bullet itself does not to this extent. This reduces case tension. The taper crimp die should only be used to remove the bell created in order to easily place the bullet on the case mouth prior to seating it.

I use beveled lead 9mm bullets and do not bother crimping at all since I don't need to bell larger than the bullet diameter for easy seating. They work nice.
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Old December 20, 2012, 07:28 PM   #23
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Well said Gerry
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Old December 21, 2012, 01:01 PM   #24
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I remember a test that we would run as a quality assurance for small arms ammo, when I was working at rock island.
It was a test on .45 and 9mm ammo used in current U.S. inventory.
We also had a contract to test “Affect of Manufacturing and Engineering Standards” for the D.O.D
The test was using load cells and strain gauges on selected test ammo in inventory and new manufacturing process.
We first started with the current issue of .45 and then the 9mm both gave the same results, within the caliber of test.
Using new military spec. brass and hard ball ammo, the bullet would be seated up to 240 psi.
Test would start with varying degree of seating pressure of the bullet from a max length each round would support. Current issue magazines would not accept the length of the round.
The bullet would be seated using a load cell and then tested. Seating pressure would have no effect on the V1 or velocity using single based powders. Now the pressure was a different story and we saw all kinds of radicals develop. The bullet would have increasing pressure on the powder.
The other test we would run is the seating strength, which includes the crimp test. A number of bullets would be seated all with the same parameters. A select number rounds would be the “Standard” and the rest tested by firing. The standard would have the bullet seated with different pressure on the crimp and case original dimension. This crimp was also measured by load cell, using Bernoulli Equation and seating coefficient frictional factors.
As the crimp went up in value of tension more radicals did appear V1 and PV3 these did relate into problems with standard deviation and pressure. Due to the decrease of diameter of the bullet, some blow by was noted in extreme cases.
Slight crimping did tend to flatten out the bell curve of V1 and pressure Deltas.
All testing was done with a piston copper crusher type barrels and velocity at a set distance of ten feet for handgun rounds.
The adhesive that was used, back then is a story all unto itself, which I will not get into here.
Some of the newer double based powder acts quite differently when crimped pressure is used, that was after my time.
Observation:
1. So seating depth has some effect on radicals which can be seen with a chronograph and calculator.
2. Crimping ever so slightly did help.

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