Plunk test

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Dewman
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Plunk test

Post by Dewman »

To Plunk test or not. Warning A little Long winded
So in my quest to reload some rounds and go out to the range I made several Noob mistakes in getting material and info for a 40 S&W .
1. Bought a Flat Point 180Gr lead bullet @ .402 without checking to see if I can find load data for it.. I learned later that there are as many molds to cast that have a different Ogive as powders to use.
Still do not know what hardness they are.

2. Gleaned what information I could from you guys here and a few other internet reloading sites. Found a load for jacketed at same or more weight and reduce your powder charge. That seems to be the normal answer on the forums..
Should have read a little farther and learned about the Plunk test..
The only powder I could find was IMR SR-4756. which did have some load data for different rounds .And is a little slower burning than the Universal that I had some of.
So I load some up @ 1.125 OAL with 6.0 of powder . Some with a normal crimp that the Lee die has and some with the factory crimp die.. When using the Lee Seat and crimp die I did notice that I shaved a little off the bullet . Tried the bench test and no bullets moved from their OAL
With the seat and crimp die set to only seat the bullet I used the FCD die to apply the crimp. With this I did not notice any shaving of the lead. Thought I was doing a good thing :)
So off to a friend's house out in the country that has a large hill at his back yard ..
We shoot up the 20 rounds that I have made up and a few other pistols.
My friend noticed that some of the holes looked like the rounds went thru sideways. He mentioned it to me and with my mind the way it is I forgot about it.
Went home thinking to myself did not notice any over pressure rounds and no unburnt powder. All the brass that I picked up looked good .
So the next day I sat down and loaded up what I have. Bad mistake for me..
That Monday at work my friend asked me if I had found any answers to why my rounds went thru the paper sideways .. That is when my head started hurting.
So I guess I have a few questions still.
With the lead round I have I removed my barrel and dropped in the round .It stood higher than it should have. Cannot think of the name of the barrel part that is measured by .
I made up a some rounds without powder or primer at different lengths .
Started with 1.120 and went to 1.090 @ 1.097 the round was still not passing the plunk test at 1.090 it was good but by then I was .035 smaller that the OAL that I find for that bullet. And that I know can cause a serious problem with pressure.
The bullet was seated enough to cover the flat part of the bullet

I have not ran a slug thru my barrel to get the right size .. I used a digital micrometer and got a reading of .401 .. Most info that I find states that the lead round should be .001 bigger than the barrel. So I should have been ok there.

Took a sharpie and marked up the flat part of the bullet and down the ogive . and gently forced it down the chamber and when it was at the right height I twisted the round . The only area that I could see any of the black removed was on the flat area just before the start of the radius.
This is being fired out of a XD 4 inch 40 S&W .
Any thoughts while I pull 12.5 LBS of lead for "The German" to melt and use in his 45 ??
Should I have sized these to .401 ??
and how important is it for the bullet to have a little running room before engaging the lands or the side of the barrel
Allways remember when in combat your weapon was made by the lowest bidder
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evan price
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Re: Plunk test

Post by evan price »

What is the diameter of the loaded round at the crimp?

Assuming a .402" bullet, the brass is roughly .010" thick so your diameter should be right around .423-.424" and if you are overcrimping the bullet it is squeezing it undersized. You did mention you had shaved lead off the bullet when seating. Undersized bullet won't seal the bore properly.

The plunk test checks two things-
1. is the length of the round short enough that the bullet isn't getting jammed into the rifling
2. Is the loaded round sized down enough that it fits in the chamber

It won't tell you the opposite of those two things, such as if the round is undersized or too short.

I have never loaded 40 with that powder so I can't tell you if it seems to be a good load or not.
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Dewman
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Re: Plunk test

Post by Dewman »

The only rounds I have left are the ones run thru the FCD die . They measure .422

It looks like they are jamming in the area just before the rifling. I believe this is called the Leade.
I used a sharpie to color the end of the bullet from the shoulder to the tip.
Looks like the only thing that rubbed was the area from the case up to where the ogive started

The round one the right is a Hornady XTP that I loaded.

http://sdrv.ms/15hY1JD" onclick="window.open(this.href);return false;
http://sdrv.ms/18BrorF" onclick="window.open(this.href);return false;

Maybe I need a bullet with a better rounded area before the ogive. Or my pistol is to tight for a .402 lead bullet.
Allways remember when in combat your weapon was made by the lowest bidder
landrvrnut22
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Re: Plunk test

Post by landrvrnut22 »

Are you belling before you seat and crimp?

If you are not belling, you may be shaving enough lead to not seat in the chamber properly. I am not familiar with the dies you are using, but are they a taper or roll crimp?

It should be a taper crimp, and it should only be enough to remove the bell. You may also be over crimping, and squeezing the lead out.

You also may have the crimp die set too low. I use some belled brass, and slowly work the crimp down to with a bullet till it is where I want it. THen lock the die. I then work the seater in to the OAL, and lock it in. I use RCBS dies FWIW.

The plunk test is fine if you only use one gun. If you are shooting in multiple firearms, you would be better off with a chamber gauge. http://www.dillonprecision.com/content/ ... Case_Gages" onclick="window.open(this.href);return false;
This will allow you to guage your rounds for firearms with minimum chamber clearances. Seat/crimp until the rim is flush.


EDIT TO ADD: Looking at your photos. I would guess you do not have enough crimp. Hard to say without seeing it in person.
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Dewman
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Re: Plunk test

Post by Dewman »

From reading different books it looks like half of my problem is with the Factory crimp die .. It is sizeing my lead down for me.. So no more with this die for lead loads
The other problem is that the has to be seated to 1.090 to fit with out the shoulder of the round round being stuck in the throat of the barrel. I bought the Lyman 49th edition and it shows a 175 gr lfp that is at 1.10 OAL ..and another at 1.090 OAL.. need to read it a bit more ..

Something tells me this boolit was not made for the 40 S&W but for something else and sized to .402 .

The other die I have does a taper crimp .. when I get time I wil post a photo of the round @ 1.090 OAL with the taper crimp.
Allways remember when in combat your weapon was made by the lowest bidder
landrvrnut22
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Re: Plunk test

Post by landrvrnut22 »

I am using the same/similar bullet, and loading them to 1.125 over 6.0gr of Power Pistol. I would say it has less to do with your OAL, and more to do with your crimp. If you were local I would show you.

I take a tumbled, belled brass, and prepare my taper crimp seating die by loosening the seating rod and backing it off 2-3 revolutions, and threading the die into my press about half way. I then cycle the handle, and seat a bullet, back it out, and check the OAL, and crimp in the chamber gauge, or barrel. I adjust as needed until the OAL is correct and the rim sits flush in my changer gauge, and falls in and out freely. Then lock everything down, and do a second test round with no powder or primer to double check. I then check the OAL every 10 rounds.

You do not run the die down all the way to the shell holder like the sizing or Bell die. The crimp is adjusted by the depth of the die in the press. As I mentioned, I use RCBS carbide dies, and the procedure may vary by maker.

Something else to check is if you are using range brass. Some Glocks, and to a lesser extent XD's have a partially unsupported chamber that can slightly bulge the brass. This can cause the rounds not to fully chamber in other guns. Usually a full length resizing die will get the bulge out, but Lee makes a special die to remove the bulge.
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evan price
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Re: Plunk test

Post by evan price »

That bullet is correct shape for 40 or 10mm.
I would first discontinue the Lee FCD. If your bullet is the right size, your brass is the right size, and your crimp and seat are correct, you don't need an FCD.
FCD's are good for guns with a very tight chamber or very picky feeding. If all the other steps are correct in the process the FCD doesn't add anything.

I would reduce your OAL. IIRC from the data I recall 6.0 grains is a starting load and it can go up to 8.5 grains? Double check that with verified factory powder data like on the Hodgdon Reloading Data Center online (I can't get to there from where I am now or I would look it up.) I also recall that 40 S&W loads run to equivalent 9mm OALs since that was a design criteria for 40 S&W originally- same size magazines as a 9mm- but again, I have never used that powder for 40s.

The FCD can and will undersize lead bullets and this will be one possible cause of the problems you are having.
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BobK
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Re: Plunk test

Post by BobK »

evan price wrote:I would reduce your OAL.
I agree. You have too much of the shoulder sticking out of the case and it is engaging the rifling.
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Orochimaru
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Re: Plunk test

Post by Orochimaru »

FWIW, I agree as well. Your OAL could stand to be a bit shorter.

The FCD discussion could easily eat numerous threads, if it hasn't already. The single biggest danger from it is brass spring-back and an undersized lead boolit. Evan Price showed me a round once that looked flawless in all regards, except the boolit could be spun in the case. The brass sprang back. It makes a fine crimp on rounds where you want a heavy crimp without risking buckling the case with a seating/crimp die -- and you can stay safe by removing the sizing ring (a reversible operation). I use one for 357 mag and 44 mag where I want a heavy roll crimp. Like Evan said, unless you've got a really picky, tight chamber, stick to good reloading technique and leave the FCD out of the equation.
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