Plunk test and 9MM CCB Brass Fail


PDA






Scuba_Steve
January 2, 2013, 07:19 PM
I've only been reloading since summer but during that time have loaded about 6 thousand rounds. My .357, .44, .45acp, and 10mm rounds have been fine, but I have had trouble with 9mm failing the plunk test.

My search here suggested marking the case with magic marker and doing so I found the cases that don't fit the case gauge were rubbing approximately
.230 from the base. When I measure the failed cases, I am unable to detect any variance from the cases that pass.

Here is where the statistics get interesting, this is based on my latest batch of 500 reoladed rounds of 9mm.


7.2 percent of the reloads failed the plunk test
12 percent of my reloads were CBC Brass (which according to my search is Magtech)
91 percent of the failures were the CBC Brass

Any suggestions would be greatly appreciated :banghead:

If you enjoyed reading about "Plunk test and 9MM CCB Brass Fail" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
jwrowland77
January 2, 2013, 07:36 PM
Yeah, don't use CCB brass if it fails at that high of a percentage.

Scuba_Steve
January 2, 2013, 07:44 PM
^^^^^
My apologies for not being more clear on my request. Any intelligent suggestions as to why this may occur would be greatly appreciated. :neener:

jwrowland77
January 2, 2013, 07:59 PM
I thought it was an intelligent response. Ill put it in terms of baseball (love that game)....

If you have a batter that bats .910 (other brass) and a batter that bats .100 or 090 (CBC brass) and game is on the line, which batter do you want in a tough situation?

(1.000 is perfect batting average)

You'd want the batter that only fails 9-10% (batter with .900-.910 average) of the time. If I was faced with your situation, I'd throw the CBC brass in a scrap bucket, but that's just what I would do.

Walkalong
January 2, 2013, 08:22 PM
Where is the round failing to chamber? Is it the bullet hitting the rifling or the thickness of the round where the bullet is seated?

Any brass should work without a 91% failure rate.

Walkalong
January 2, 2013, 08:25 PM
I found the cases that don't fit the case gauge were rubbing approximately
.230 from the base. When I measure the failed cases, I am unable to detect any variance from the cases that pass. Missed that. There must be a bit of difference. Is the sizer all the way down? With the tapered case that really makes a difference.

bds
January 2, 2013, 09:13 PM
marking the case with magic marker and doing so I found the cases that don't fit the case gauge were rubbing approximately .230 from the base.
How about considering these?

1. Take some CBC cases and check them with the case gauge after being resized only (NO BULLET). They should all pass the case gauge but if they don't, they are not being full-length resized and you need to adjust the resizing die. When the resizing die is at the bottom of the ram cycle while resizing a case, do you see any daylight between the bottom of resizing die and the top of shell holder/plate? If you see daylight, you may need to lower the resizing die.

2. If the bottom of the resizing die is already "barely kissing" the top of the shell holder/plate when the case is being resized, and the resized cases still fail the cage gauge, then these CBC case bases were expanded too much to be resized and they should be tossed in the recycle bin.

3. Take resized cases that ALL passed the cage gauge and make some test rounds. If they all pass the case gauge, the problem was with the resizing step. If any don't pass the case gauge, paint the case with marker and check to see where it is rubbing.

Let us know what you find.

Skinnedknuckles
January 2, 2013, 09:40 PM
I think BDS is on the mark for troubleshooting when the problem occurrs. Assuming that the problem is occurring after loading instead of in the resizing step, the case may be bulging/buckling during crimping. Have you measured the length of the CBC brass and compared it to the length of the other brands. Also, are you using the Lee Factory Crimp Die, or something equivalent, that is designed to iron out any post crimp bulge? I haven't reloaded any CBC brass to date (haven't collected enough yet) but I appreciate the heads-up to check for similar problems.

Walkalong
January 2, 2013, 10:25 PM
If you check the brass as bds suggested, then you will know if it is a sizing issue, or loading issue.

You might have a tight chamber. I have one 9MM that needs brass that can pass the Wilson case gauge. My others will swallow up much fatter rounds.

http://www.thehighroad.org/attachment.php?attachmentid=114165&stc=1&d=1264566765

Scuba_Steve
January 2, 2013, 11:11 PM
Thanks for the constructive comments. Tonight I loaded 200 rounds of non CBC brass with no sizing issues. The dies are dillon and the sizing die is all the way down to the shell plate.

I will take the advice and resize a bunch of CBC cases, check for fit. If they all fit, I will check case length, load them and check size again.

It will likely be a few days, but I will report back.

gamestalker
January 3, 2013, 12:18 AM
I've used that brass before and didn't have any problems in numerous pistols. It doesn't last very long though. It sounds to me like you aren't getting the bullet seated deep enough to fit your chamber, or, you are not getting it comletely resized.

GS

Scuba_Steve
January 4, 2013, 09:50 AM
Well, here is an updated. I seperated the CBC brass from the other brass. I loaded another 300 rounds of the non-cbc brass, no issues.

I then resized 60 CBC cases and everyone fit the case gauge fine. After this, I loaded 5 of them and 4 failed to fit in the case in the case gauge.

The only difference I can find between the CBC brass is thickness. The CBC brass is approximately .030 thick and my other brass is .040 thick. This one really has me baffled.

Walkalong
January 4, 2013, 11:17 AM
Did you try the sized cbc brass that fit the gauge in your chamber? If it fit that as well, the problem is the diameter where the bullet is seated, not near the web. Look at seating procedures or bullet diameter.

bds
January 4, 2013, 12:31 PM
Yes. So now adjust your seating and taper crimp dies with the CBC brass so the finished CBC rounds will pass the case gauge.

Once that's done, non-CBC brass should pass the case gauge as well.

Keep us posted.

Hondo 60
January 4, 2013, 12:38 PM
Sounds like you may be over crimping.
That can crush the case in odd spots.

OR

Are these cases fired from your gun?
Is it a Glock?
Could be you need a "Buldge-Buster"

Just throwin out some things to check...

Good Luck!

bds
January 4, 2013, 12:55 PM
Could be you need a "Buldge-Buster"
Not the push-through Bulge Buster kit but the FCD may work to fix the finished rounds if the OP can't adjust the seating/taper crimp die so CBC rounds pass the cage gauge.

Lee does not make the push-through resizing "Bulge Buster" kit (http://leeprecision.com/case-conditioning-tools/lee-bulge-buster-kit/) using the FCD for the 9mm because 9mm is a tapered round (case mouth diameter is smaller than case base rim diameter). They are only offered in 380 ACP, 40 S&W, 45 ACP, 45 Win Mag, 10 mm, 41 AE and 45 GAP.

This is a response from Lee Precision (http://www.thehighroad.org/showthread.php?p=6358308#post6358308)

From: John Lee <info@leeprecision.com>
Subject: Re: Bulge Buster Die Kit
Date: Wednesday, February 3, 2010, 7:49 AM

... Because the 9mm [case] is tapered the standard Factory Crimp Die will not work as a push through die.

Sincerely

John Lee, President

mdi
January 4, 2013, 01:54 PM
Well, here is an updated. I seperated the CBC brass from the other brass. I loaded another 300 rounds of the non-cbc brass, no issues.

I then resized 60 CBC cases and everyone fit the case gauge fine. After this, I loaded 5 of them and 4 failed to fit in the case in the case gauge.

The only difference I can find between the CBC brass is thickness. The CBC brass is approximately .030 thick and my other brass is .040 thick. This one really has me baffled.
Well, you've narrowed it down to one step of the process. Sized brass fits, bullet seated, case doesn't fit. Now, why doesn't if fit after bullet seating? Case walls thicker than other brass and bullet expanding case OD larger than chamber?

Trouble shooting reloading problems isn't magic, just common sense. Bottom line, a cartridge is a peg and a chamber is a hole. To get a peg (cartridge) to fit in a hole (chamber), it must be smaller than the hole (chamber). Is your peg larger in diameter than the hole? Is your peg longer than the hole? Is the tip of the peg hitting the bottom of the hole (bullet hitting rifling)? Does your peg have a ridge that's larger than the hole (too much flare remaining)? No offence, but it's as simple as that.

gamestalker
January 4, 2013, 03:45 PM
Try resizing a case, chamfer the inside of the mouth evenly so the bullet will seat straight and without shaving, and then seat a bullet without belling or crimping the case. This would eliminate the crimp or belling as the culprit.

I seat all my bullets in this manner.
GS

Scuba_Steve
January 4, 2013, 04:26 PM
PROBLEM SOLVED....

After checking the thickness of the brass and finding the CBC brass .010 thinner, I started thinking "what could be making it bulge".

I am loading AA7 at 7.0gn which while the minimum load in Lymans 49th, it really fills the case. So I switched to AA5 at 5.3 gn, loaded 100 cases, no issues.

I guess I'm switching to AA5 for 9mm now.

flyskater
January 4, 2013, 04:56 PM
I place CBC brass where it belongs since I have had 2 failures with them. They belong in the trash.

If you enjoyed reading about "Plunk test and 9MM CCB Brass Fail" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!