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All 9mm Failing Plunk Test and Gauge Checker


Orion1

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Hi, I am new to reloading. All (but one) of my 9mm is failing both the "plunk and turn" test and the case gauge checker test. I have not installed the primer nor the powder.

 

One round has passed the "plunk and turn" test and case gauge checker, however I didn't write down what I did that allowed it to pass. Not sure if its the press now..

 

The setup:

Dillon 550B Reloading Press

Dillon 9mm Carbide Reloading Dies 14406

KKM 1:32 Match Grade Barrel 

EGW 7 Bullet Case Gauge Checker

 

The Components:

Brazos 115gr bullets in 0.356"

Starline or Federal brass, once fired

 

The Process:

  1. Brass is inspected and cleaned 
  2. Pre-sizing
    1. Brass passes the case gauge checker without sizing
  3. Re-sizing
    1. Brass passes the case gauge checker and can be dropped/turned inside the gun barrel
    2. Brass measures 0.377" at the head and ~0.387" at the bottom
      1. Was thinking the bottom "bulge" was the issue, however after putting brass through the resizing stage, I would test it via the case gauge checker / barrel turn test and it passes. 
  4. Expansion
    1. The brass mouth is expanded properly so a bullet can be seated with minimal bell shape
  5. Seat
    1. The bullet is seated in the brass mouth. There are no burrs, noticeable signs of crooked bullet placement
    2. OAL is ~1.128. 
  6. Taper Crimp
    1. Crimp is applied and measures 0.376" to 0.377"
    2. OAL is ~1.128. 
  7. Plunk Test / Case Gauge Checker
    1. Fails. The round sticks slightly outside of the barrel or case gauge.

 

Other Tests:

  • I've also used just brass and no bullet going through the same process (no bullet is seated) steps 2 through 7 and it passes.
    • I'm thinking the issue is with the seating die, so I repeated steps 2:7 testing various seating parameters. I've seated bullets from 1.1 to 1.38. All fail. 
  • I've removed bullets from Atlanta Arms and Winchester rounds and replaced the Brazos bullet with either of these two and it still fails both tests. 
  • I've removed brass from AA and WIN rounds to see if it was a brass issue and rounds fail both tests.
  • AA and WIN manufactured ammo passes both tests, so the problem is not in the barrel or gauge checker.
  • I purchased a new Dillon 9mm die set to replace with the existing one. It will arrive today, so I might switch these out to test if the dies are having issues.

 

I'm out of ideas at the moment. I'm going to try to load 45 to see if I have the same issue to understand if the problem might be in the press itself. Any help would be greatly appreciated. I've been working through this problem for two weeks and cannot find a solution.

 

Photo of round after going through steps 2:7.

Fails plunk test, sticks out slightly from barrel. Makes a straight mark through the sharpie at the base of the round on the brass. I disassembled this exact brass, removed sharpie, resized and it passes case gauge checker... Not sure what to do.

https://ibb.co/9cxmqLc

Edited by Orion1
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Orion- One thing you can try if you are not already there. Run your press’s shell holder all the way to the highest position and then screw your resizing die down until it makes full contact with the shell holder. Lower your shell holder and then give your resizing die another 1/8 turn. 
 

This refers to a process that is called - camming over
 

Not saying this will fix the issue but it will get you cases closer to being fully resized and that might be your issue.  

Edited by Sigarmsp226
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So after sizing your brass a case without a bullet will plunk ok as well as pass the case gauge.

 

Then the black magic marker test with a seated bullet shows interference at the base of the case.

That same test does not indicate any problem at the case mouth or any interference with the rifling doe to excessive OAL.

 

Your initial base diameter measurement of ~0.387 seems reasonable and is actually tighter than what I typically see with my brass.

 

However after seating a bullet it will no longer pass either the pluck test or the gauge.

 

hmmmm.... 

 

I'm trying to envision how seating a bullet would affect the base diameter of a case enough to cause this problem.

 

It seems as if the case isn't getting sized down low enough but the fact that the brass without a bullet plunks seems to say otherwise.

 

 

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Based on the picture you provided it doesn't look like the bell is removed from the case. Could just be the angle of the picture but double check your measurement there. 

 

Also looks like your sharpie is scratched off the rim of the case as well

Edited by CC3D
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Here’s the process:

 

  1. Clean and resize.
  2. Make dummy rounds without primer or powder to check final OAL.
  3. Adjust OAL until plunk test passes. 
     

 

From all the descriptions you have two issues, OAL and removal of crimp.

Don’t think crimp based on diameter but rather on removal of the crimp.

OAL is never determined by what is read from a book. It is solely based on the gun chamber and chosen bullet.

 

Taper crimp dies work best on most cartridges, I personally like the Dillon taper crimp for 9mm. 

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I’m thinking that after you seat the bullet and not removing the flair it’s a little bit bulged on one side and the flair is pushing the back of the case into the bbl. Sort of crooked. Once you crimp properly I think your problem will go away. Don’t be afraid to put a bit of a crimp on them say .0005-.001 at the very mouth edge. Most of mine run .375-.376 at the edge. 

Edited by Farmer
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Don't be bashful with flare, be sure the bullet is seated without scraping.  Brass life is a distant second.

Don't be afraid to crimp.

 

That bright ring near the case head is why I use a Lee CFC die; the generous radius and flare on my sizing die needs help.

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41 minutes ago, HesedTech said:

Here’s the process:

 

  1. Clean and resize.
  2. Make dummy rounds without primer or powder to check final OAL.
  3. Adjust OAL until plunk test passes. 
     

 

From all the descriptions you have two issues, OAL and removal of crimp.

Don’t think crimp based on diameter but rather on removal of the crimp.

OAL is never determined by what is read from a book. It is solely based on the gun chamber and chosen bullet.

 

Taper crimp dies work best on most cartridges, I personally like the Dillon taper crimp for 9mm. 

 

39 minutes ago, HesedTech said:

Fix the crimp and OAL first then look at the base.  9mm is a tapered, not a straight cartridge. 

Have to agree with @HesedTechon this one.  If your pic is what your finished rounds look like, then you ARE NOT removing the bell with correct taper crimp!  Also, IMO, your OAL is too long.  Currently using 1.108" OAL with my 1:16 twist KKM Match barrel.

 

Follow this to fix your OAL.  Applies to any 9mm pistol barrel:

 

https://czfirearms.us/index.php?topic=103620.0

 

Then follow this post to fix your taper crimp:

 

https://czfirearms.us/index.php?topic=78873.0

 

HTHs!

 

:)

 

 

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From the article I posted above.  This has ALWAYS worked for any nominal sized bullet combination I have loaded in 9mm!

 

Quote

Therefore the above observations spawn several thoughts:
• First, that a good and truly useful taper crimp diameter for any auto cartridge is going to be 0.002-0.003" less than the case mouth dimensions shown in the SAAMI drawings. That makes the useful taper crimp dimension for 9x19 Luger equal 0.380 minus 0.003, or in the range 0.376-0.379", with most people using 0.377-0.378".

 

🤔

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Undercrimping is very common.  I get ammo frequently from people that say they crimped it to spec and think the case gauge is defective, yet when I throw them on the optical comparator, the case mouths are flared like a trumpet.  Bullet makers like to put out dire warnings about over-crimping, but 30,000 PSI on the ass-end of a bullet is going to swage most any crimp right back out as you fire it, so for our game, pretty much anything crimp-wise that fits the chamber will be fine (barring sintered bullets and the like).

 

It's a little tricky to measure crimp well if you don't have good calipers and good technique or a micrometer, so I usually suggest getting hold of a good 10X eye loupe (cheapies are <$10 on Amazon, the Belomo and Bausch and Lomb ones will run you more but are like buying a nice rifle scope instead of a NC Star).  You can use phone magnifiers and digital microscopes as well but they can be twitchy to see what you need to see.

 

Once you get one, grab a factory round that works and get an eyefull of the gap between bullet and case.  Replicate that on your ammo.

 

The bright ring around the case mouth on your pic is the crimp interference.  Probably then it tipped the round a little causing the other scrape.

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am gunna jump on the dog pile.  I was busy earlier today and so didn't comment.

 

without looking at the pictures I knew you had not removed the flare from your cases/ammo.

 

terms... Flare is case mouth opened. 

Straight wall is what your sizing die does.

Crimp is the case mouth turned in, like a 38 special case.

Using those terms 9mm is only returned to straight wall. 

 

To seat a bullet you have to flare the case.   After that, you need to push that wall back to straight...

In other words, remove the flare, ALL the flare. 

 

We call that die a 'crimp'  out of habit.

After all, who wants to de-flare ammo?

 

and I agree with this:

listen to Shred ^  He knows what he's talking about.

 

miranda

 

 

 

 

 

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8 hours ago, Sigarmsp226 said:

Orion- One thing you can try if you are not already there. Run your press’s shell holder all the way to the highest position and then screw your resizing die down until it makes full contact with the shell holder. Lower your shell holder and then give your resizing die another 1/8 turn. 
 

This refers to a process that is called - camming over
 

Not saying this will fix the issue but it will get you cases closer to being fully resized and that might be your issue.  

 

I've tried adjusting the resizing die as such, no luck, thanks for the tip though. 

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Try seating a projectile quite a bit shorter and see if the problem disappears.

Also, try a different projectile if you have any.

Projectile ogive interference with the barrel may be an issue that is not showing on your tests.

Edited by DownUnder
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3 hours ago, DownUnder said:

Try seating a projectile quite a bit shorter and see if the problem disappears.

Also, try a different projectile if you have any.

Projectile ogive interference with the barrel may be an issue that is not showing on your tests.

 

I purchased a box of Hornady 0.355" copper FMJ and they all pass... I'm having a difficult time thinking 0.356" doesnt seat properly with my KKM Match Barrel. I contacted Brazos and they replied fast saying, "Possibly the cases are not beveled out enough/open up enough before you started reloading. Also, it’s rare, but you might need 0.355”.". 

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19 hours ago, Farmer said:

I’m thinking that after you seat the bullet and not removing the flair it’s a little bit bulged on one side and the flair is pushing the back of the case into the bbl. Sort of crooked. Once you crimp properly I think your problem will go away. Don’t be afraid to put a bit of a crimp on them say .0005-.001 at the very mouth edge. Most of mine run .375-.376 at the edge. 

 

Thanks for the input here.

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17 hours ago, GrumpyOne said:

Where on the finished round are you measuring your "crimp"? As others have said, you have not removed the bell / flair that you put into the case to seat the bullet head. 

I am measuring the crimp on on the head of the case, closest to the bullet. When I crimp it more and the bottle resembles a coke bottle is this an issue?

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1 minute ago, Orion1 said:

I am measuring the crimp on on the head of the case, closest to the bullet. When I crimp it more and the bottle resembles a coke bottle is this an issue?

The "coke bottle" effect has been discussed many times............

 

👍

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51 minutes ago, Orion1 said:

I am measuring the crimp on on the head of the case, closest to the bullet. When I crimp it more and the bottle resembles a coke bottle is this an issue?

"Mouth" of the case. The case "head" is the part of the case the primer goes in. 

 

What I meant was, where on the case mouth are you measuring? You need to measure on the very, very end of the case mouth, as close to the bullet as possible. The easiest way I have found to do this (with calipers, anyway) is to measure the case with the calipers parallel to the case, not at a right angle. Where the caliper jaws are over the bullet, inline with the case, using just the very tip of the calipers. I bet if you did this, your measuement would not be the .376- .377 you claim.

 

The coke bottle shape is actually desired when reloading. It prevents bullet setback.

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