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Bullets are keyholeing on target


Bench

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This is all driving me crazy.  If a bullet is .356, and the shell is .011 thick, then without any crimp or any pressure the mouth of the bullet will measure .378.  At .378 you should be able to just pull the bullet out with your fingers.   The first .300 of the shell is usually straight walled inside.   I expand this area to only .354 inside and give the mouth a little more flare.  Now, it looks like the .354 expansion area plus wall thickness of .022 would make the shell .376, but, the .356 bullet pushes back and the diameter of the shell is .378 and the bullet is held firmly.  Reducing the flare to .378 does not hold the bullet at all.  So, would reducing the flare area to .377 sound reasonable enough? 

Edited by Wheeljack
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1 hour ago, Wheeljack said:

This is all driving me crazy.  If a bullet is .356, and the shell is .011 thick, then without any crimo or any pressure the mouth of the bullet will measure .378.  At .378 you should be able to just pull the bullet out with your fingers.

 

Look above at the bold text in your quote.  There IS pressure, or more accurately: case neck tension. 

 

The resized 9mm case with no bullet present does not have a  case mouth diameter of .358.  It's smaller than that prior to bullet seating.  That might be  what's left after bullet seating, depending on bullet diameter, I suppose. 

 

But more importantly, the inner diameter of a resized case is smaller than .355.  If it weren't, you'd be able to slide a .355 bullet right in, but you can't.  I don't know off the top of my head what the inner diameter of a properly sized, healthy 9mm case is, but I know it takes quite a bit of force under the reloading press to push that bullet in and stretch the neck outward.  And it's that residual neck tension left over by stretching the neck open that holds the bullet in place, which is why people are constantly telling others that taper crimp dies are just to remove the bell/flare. 

 

The case mouth should be flared enough to accept whatever bullet you are using, based on bullet diameter and bullet type, with the intent of not harming the bullet. I've seated plenty of .355 JHP without flaring the case mouth at all, where the slight bevel on the bottom is enough to get the bullet in without damaging the case mouth, but a .356 plated bullet needs some, and a .356 coated lead bullet needs a little more, and a .357 coated lead bullet needs a little more than that. 

 

I have never measured flare.  I adjust it to the bullet I'm loading at the moment. And if I scrape some coating on a few bullets before I dial it in, those bullets are for practice. 

 

But for crimp, you can set that at .376 or .377 as you like for .355 bullets, and adjust up a thousandth for every thousandth up in bullet diameter, OR you can set crimp for .379 and forget about it. Crimp does nothing to hold the bullet in place, and .379 will work fine with every bullet you load.  If you want to adjust crimp later on to try to tune for accuracy, knock yourself out,  but it's not necessary to get accurate loads. A crimp of . 379 will work for everything, and .378 will work fine for everything except the really oversized bullets.

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I think we have it now.   Details:  I'm using .356 plated bullets.  I use a NOE expander die.  I insert it into the shell .300 deep.  The deeper part of the die is .354 and gives the inserted  bullet a good grip.  But I like the die because it opens the mouth of the shell to .358.  It makes inserting the bullet easy and straight, but I do loose tension at the mouth of the shell.   So I give the mouth of the shell a small crimp to .377.    As you explain the crimp or the lack of it,  it works for an expander die with no flare.   So because of the NOE die that I use, I have to crimp a little.  With other dies, you are right on target, and I understand and agree with what you taught me.  Thanks.

(I hope the storm misses you)

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Metals have a property called "spring back" that is exactly what it sounds like. When you flex metal, it will spring back to some degree, possibly all the way, possibly some of the way, dependent on how far it was flexed and the particular properties of the metal. 

 

When you erase the bell from the case mouth with a taper crimp die, you're not regaining neck tension right there at the mouth.  You might get it flush and get it to touch, but the Itty bit of spring back will negate the tension right there at the mouth.  There's nothing you can do about that.  To create neck tension there, you would have to crimp past flush to account for the tiny bit of spring back, and that would damage a coated lead or plated bullet.  Neck tension right up there at the mouth is lost with the flare.  And it's not regained with crimp.  And it's not a concern.  You still have the other 99% of the bullet below the case mouth getting firmly and lovingly hugged by the case. ;)

 

Another way to understand that is simply that the neck tension comes from seating a bullet in the case that is larger than the inner diameter of the case, stretching the case.  Since taper crimp only takes it back to flush, which can't create or increase neck tension. 

 

I use a Redding expander die, which is a copy of the Lyman M-die.  It has a plug that expands into the case, like your NOE die, but it has a flare at the top that allows me to control how much flare there is.  But again, I don't know how much flare there is by measurement - - I never measure it.  I just tinker until it's right. 

 

I would also suggest that with you, you should measure before and after a bullet is seated.  If it flares to .358 before the bullet is seated, it will be bigger than .358 after the bullet is seated because the bullet will expand the entire case.  So if it's greater than .358 after the bullet is seated, then .357 may in fact be over-crimped.  You might be better taking it down to only  .358 or .359, depending on the flare diameter after seating. If it Is  .358 after bullet seating, then I suppose .357 is the way to go. 

 

 

Edited by IDescribe
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Got it.   I do like the flare the NOE or M dies give, as it helps me seat the bullet straighter, but I will have to give the flare diameter a minimum seating depth.  Then after I seat the bullet, reduce to flare to create a straight shell. 

 

Thanks all.

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On ‎5‎/‎25‎/‎2018 at 7:08 PM, IDescribe said:

 

YES that is way too much crimp.  You should not see a ring, and that bullet looks outright pinched. 

 

Set taper crimp for. 378 and be done with it. 

 

And if using Lee FCD, stop and get a regular taper crimp die. 

 

What would you say is the downside with the LEE Factory Crimp Die compared to lets say the LEE Taper Crimp Die?

https://leeprecision.com/carbide-factory-crimp-die-9mm.html

https://leeprecision.com/taper-crimp-die-9mm.html

 

I am currently using Dillons taper crimp die.

 

Edited by Ludde
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L, the only difference between the two is the FCD sizes the case .  You can adjust the amount of crimp in either.  9mm guns are problematic in a couple of ways.  First, the case is tapered.  Second, bore sizes are all over the place, ranging from .355 on the tight end to .359 on the sloppy end.  The OP says he needs .358 bullets to match his bore and correct the tumbling problem.  The FCD will size the bullet down to .355 (depending on case wall thickness), and that can affect accuracy.

 

I have tested this in my 40sw guns.  I use the FCD in 40sw because it eliminates the Glock bulge.  It is a straight walled case, so there are no problems on that score.  My favorite bullet is the Rainier 155gr copper plated at .400".  I am not permitted to use anything but lead or poly coated on steel at one of my clubs, so I switched to poly.  The rainier gave me same hole groups at 15 yards (from a rest).  The original Gen1 Precision bullet did the same.  It was .400".  The new Gen2 bullets are sized at .401".  The FCD reduces that to .400" on the portion of the bullet inside the case.  This affected accuracy.  I now get one hole groups of almost 1" outside to outside.  I haven't tested 9mm yet.

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  • 6 months later...
On 5/1/2018 at 10:13 AM, Beef15 said:

That's a coated bullet right?

Like others said, probably too slow.

3.0-3.3 is a pretty standard range for Titegroup with that weight cast/coated bullet. I don't understand why but my Lyman book lists way lower, like stock sprung gun don't function low.

Determine OAL by plunk test, 1.058 is very short.

0.376/0.377 "crimp" should be in the ballpark, maybe a touch tight but not enough to matter.

Your magnum primer shouldn't hurt anything but is unnecessary.

 

In light of the short OAL and magnum primer I'd probably bump to 3.0 chrono, work from there.

 

Don't know how many you shot, but check the bore for leading or other heavy fouling.

Was just going through some old posts and saw this. I suppose all is good now but I was shooting TG with Hi-Tek coated bullets. Started noticing less accuracy over time and found the TG was hot enough to burn off the coating on the back of the bullet which is where the lead was coming from.

Switched to Alliant Sport Pistol, no lead issues now, and much cleaner shooting...

IGG

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4 hours ago, IGOTGLOCKED said:

Was just going through some old posts and saw this. I suppose all is good now but I was shooting TG with Hi-Tek coated bullets. Started noticing less accuracy over time and found the TG was hot enough to burn off the coating on the back of the bullet which is where the lead was coming from.

Switched to Alliant Sport Pistol, no lead issues now, and much cleaner shooting...

IGG

Thanks IGG, you're correct, no more keyholing but I just may begin to investigate Alliant Sport Pistol. Do you have any recommendations for loads for 9mmx124 coated with Alliant Sport Pistol? Thanks!

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19 hours ago, Bench said:

Thanks IGG, you're correct, no more keyholing but I just may begin to investigate Alliant Sport Pistol. Do you have any recommendations for loads for 9mmx124 coated with Alliant Sport Pistol? Thanks!

Bench, can't say brother because I shoot 145 gr coated .356 (Acme). Theoretically a projectile should require a pinch more power to match the same pf.

I do sort my brass by head stamp as I found the coal is more consistent.

G19 gen 4; I'm all about defensive cc and I compete with what I carry.

145 gr .356 Acme

3.2 SP

CCI SPP mag primers (mag only because I was offered too good of a deal to pass up) perhaps 15+/-  fps more so not significant.

1.150 coal

.380 crimp

99.99% pass plunk & spin in my barrel's chamber (I don't use a case gauge) - the rare ones that don't pass are just run back through the 650 an bingo.

This recipe makes 133 pf 

Cheers!

IGG

 

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  • 3 weeks later...
On 12/20/2018 at 12:33 PM, IDescribe said:

 

How?

ID, apologies. Have been covered up. First I read it, then I looked for the projectiles I shot at a range that that I am a MD at for IDPA & Pins matches, it has a backstop of what appears to be ground up rubber. Not difficult to find. Prior to this I couldn't figure out why my barrel had lead in it...

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