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Old November 23, 2019, 08:06 PM   #1
kmw1954
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Plunking problem

I have recently started working with my own cast bullets and don't now understand what happened with this load workup.

Started slow with some cast bullets that were supplied by a member on another forum and got to a point tat they were working very well in both of the 380 pistols I loaded these for. The bullet is from a Lee 356-102-R1 mold.

From that point I purchased my own mold and started cast with it. After talking with the person that cast the originals I thought I duplicated everything pretty close. The only deviation was the alloy. He used range scrap, I used cow's.

When I finally got to the range to try these I started having all sorts of feed problems with the S&W EZ.

So today I pulled the dies apart and cleaned everything and pretty much started over. Only this time I started with a few powder coated bullets as a baseline bullet.

Started with a few sized cases and checked fit in the chamber of both guns, all good. Then flared the cases w/o a powder measure in the Lee die. From there the case would start into the barrel but would not fully seat as expected. I then took the PC bullet and started seating with the die adjusted with just enough crimp so the case would seat into the barrel. Then slowly started working the bullet down.

This time I was able to plunk this bullet into the Witness barrel at .985" instead of the .960" I had come to before. Then I tried this in the EZ barrel and it wouldn't quite seat all the way and I could tell the bullet was hitting. From there I seated down to .970" and this bullet was plunking easily in and out of both barrels. So I quickly set up another exactly the same and it to plunked just fine so I tried to shorten it up some more to try and get to the .960" that I had been using. I got to .965" and again this bullet would no longer plunk and would hang up when I turned it upside down. At .960 experienced the same thing.

Now I have no idea why this is occurring other than at .965" it is too deep and is bulging the case at the base of the bullet. Though I have shot over 100 rounds loaded at .960" in the EZ that came from those sample bullets I had received.
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Old November 23, 2019, 10:13 PM   #2
big al hunter
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Where the original cast bullets also powder coated?

My best guess is that the coating is thicker this time around. For this reason, I run my cast and powder coated bullets through a Lee bullet sizer to get them back to the proper diameter.

It is also possible that the new lead alloy is doing the same thing. Measure the bullets at the base, and ask your friend that supplied the bullets to measure his.
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Old November 23, 2019, 11:38 PM   #3
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big al hunter, I have 3 different samples of the same bullet. One is sized and tumble lubed to .356, the PC sample has also been sized to.356 after coating and they are the ones I cast which are also tumble lubed and sized to .356.

I have measured the length of the bullets and their diameters and with just a .000 place caliper I cannot discern a size difference.

I am also loading these on a Lee 3 hole turret press and each finished round is measured for length before being put into the box. Also as this is a work up all the bullets were weight sorted into groups with a variance of .04gr.

I was called away before I could try this same setup with a tumble lubed bullet but hope to test that yet tonight before I go to bed.
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Old November 24, 2019, 11:18 AM   #4
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When you get a chance, try coloring the case with a sharpie or magic marker. Then force the plunk test to go to proper head space. Push the round back out with a dowel and see if anything scuffed the marker. That will show exactly where the case is sticking, identifying the source of the problem.
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Old November 24, 2019, 01:32 PM   #5
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I had a problem with a 0.356" diameter bullet approximately 3 years ago.

I bought the Lyman mold as it was a bullet design that I wanted to try in 9mm.

The bullet cast 135 gr with my alloy and the cast diameter was 0.358" at a BHN of 9-10.

I loaded maybe 20 of them and decided to check fit to chamber (plunk test them), and none of the loaded rounds would go into the barrel or into battery.

I have an RCBS lube/sizer and a SAECO lube/sizer. I was using the RCBS to size these guys.

Turns out I either had to reduce the OAL to a ridiculously short OAL to get them to fit, but knowing not to do that with such a small sized cartridge, investigated further.

Turns out the front portion was not being correctly sized and was larger in diameter than the base of the bullet.

I don't mind a base being larger than the front, but not the other way around.

What I did to remedy the problem was to size the bullet nose first, or as you might say upside down.

That solved my problem.

If I would buy a push thru sizer die, the problem would be solved as well, but I am not inclined to add more pieces to the arsenal.
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Old November 24, 2019, 02:07 PM   #6
T. O'Heir
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"...I used cow's..." Cows plural? Or a cow's what? snicker.
.985" is actually 1 thou over SAAMI Max OAL for the .380. Very much doubt that's the issue though. Far more likely to be a crimp related thing. Said crimp must be a taper crimp only, of course. Not having just the right taper crimp can cause feeding issues. Plunking is just a simple way to test that.
Cleaning one's dies regularly isn't a bad thing. Especially with cast bullets.
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Old November 24, 2019, 05:41 PM   #7
kmw1954
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The cow's must have been an auto correct as it should be COWW's.

Somehow I don't think I am being clear with this. The original load developed with the samples I received were loaded to .960" and they fired just fine in the S&W 380EZ. I know this because the day I tested I had left the magazine for the Witness on the bench from when I had the gun apart for plunk testing. So the only gun I test fired these in was the EZ. I shot over 120 of these w/o incident that day and was actually quite pleased with the results I achieved.

After purchasing the same model Lee mold and casting a bunch then sizing and lubing I assembled these the exact same way as previous as the press was still set up from the workup. As I loaded these I would plunk test in the Witness barrel and all was good and assumed that the EZ would also be still good.

Upon test shooting these new bullets that I had cast they performed flawlessly in the Witness though would not run very well in the EZ. I had 2 incidents of jams inside the magazine where the round did not even feed up to the chamber. The many rounds that would not allow the gun to go into full battery.

After returning home is when I retested the rounds for Plunk into the EZ barrel. They would not fully seat and would not drop back out.

So how does a load go from working perfectly fine to not working when the only change that I can think of is the alloy of the bullet? Unfortunately I do not have any of the original loads left, they were working so well I shot them all up. I have never experienced anything like this before.
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Old November 24, 2019, 07:39 PM   #8
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Without any of the original bullets, it's hard to identify what's different.. I use case gauges to test my handgun handloads. The problem "passing" that test is most often due to slightly bulged cases from bullets not seated straight. Not saying that's your problem, just saying that is what I most often see.

Second most common problem for me is not resizing the case down far enough. This typically only happens if the sizer isn't screwed down far enough. But I've had some brass fired in loose chambers that couldn't be sized down far enough with one die, but another die with a bit less radius at the opening did size them enough.

Perhaps it's worth noting that nearly all finished rounds that fail the case gauge test will pass a plunk test in my barrels/chambers. Probably because the case gauges supposedly represents a minimum chamber and the actual barrel/chambers are larger than minimum.
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Old November 24, 2019, 11:33 PM   #9
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Again I must clarify. I do still have bullets left from the samples I just do not have any of the finished loaded rounds. as for the bullets themselves, side by side I cannot tell them apart and as I mentioned in post, I cannot measure a difference.

Without being able to find an explanation is guess I will now just load some more to test and set these to .970/.975" and if they work I'll be happy and file this way as an anomaly.
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Old November 26, 2019, 02:41 PM   #10
T. O'Heir
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It's not unusual for one pistol to like one bullet while another does not.
"...The only deviation was the alloy...." That can be enough. And there's rarely any rhyme or reason to any of it. Absolutely no 2 firearms will shoot the same ammo the same way.
"...set these to..." It's not the OAL. It's the amount of taper crimp. Set the OAL to .984" and use just enough taper crimp to hold the bullet in place.
You can forget the case gauge test and use the chamber. Easier to take the barrel out.
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Old November 26, 2019, 08:59 PM   #11
kmw1954
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With having multiples of each caliber I own I have tried to make it a habit to build my loads so that they work in all guns. So though they may not be optimum for any one gun they will perform satisfactory in all of them. If a bullet won't work I'll load what I have and then move on to something that will. In handgun bullets there is a plethora to chose from.

Again my confusion comes from once having a load that work very well to suddenly not working at all. This second loading of this round has been a complete failure in the EZ pistol after it worked so well previously.

When I originally loaded these I had to seat these down to .965 to get them off the rifling, fully seat and pass the barrel plunk test. This time when seated to that .965" depth they would not plunk and they would not chamber. Though just moving the bullet back out .005" to .970" and they plunk the barrel just fine.

Right now I am working on some new .452" 200gr LSWC that I just cast and as soon as I am finished and get to shoot these I will also get to shoot the 380's I loaded up that were Powder Coated. I have about 50 of those and then another 20 of my tumble lubed loaded longer.
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Old November 27, 2019, 05:51 AM   #12
BBarn
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Finding success with longer OALs suggests the problem is case bulge at the bullet base. Internal case dimensions vary as well. Are you using the same pieces of brass each time? Mixed headstamp?
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Old November 27, 2019, 11:55 AM   #13
kmw1954
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BBarn that was my original thinking also though I cannot prove it one way or the other. Brass used was all sorted headstamp. When working up loads I try to stay as consistent as possible. Weigh every powder charge and measure every round before it goes in the box. And in the case of these cast bullets I was plunk testing every round in both barrels. Then I guess I got sloppy and the second session just weighed and measured as the press was still set up from the previous session and the only change was the bullet. From the sample casts I received to the ones I cast myself.

But still that does not explain why the longer seated bullet will now reliably seat whereas the others would hit the rifling.
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Old November 30, 2019, 09:55 AM   #14
big al hunter
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Quote:
But still that does not explain why the longer seated bullet will now reliably seat whereas the others would hit the rifling.
Having a longer seated bullet that plunk tests good and a shorter length that does not has nothing to do with the rifling. It is likely a bulge in the case at the base of the bullet. The case walls taper slightly thicker toward the case head. Seating the bullet deeper causes a bulge that is wider. The new cast bullet is just enough harder alloy to not deform the bullet during seating. The only other possibility I can think of is that the mold you got is throwing a slightly longer bullet. Measure the new and old and make sure they are the same length. If the new bullets are longer, the same problem would present.

After typing this I reread the line that I quoted....when you say "others"...is that the new bullets seated deeper, or the old bullets seated further out? If it is the new bullets, are you seeing marks on the bullet from the rifling?
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Old November 30, 2019, 06:01 PM   #15
kmw1954
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Bullet 1 original sample, sized to .356" length is .480"
Bullet 2 my casting, sized to .356" length is .373"
Both are tumble lubed

The bullet I have here from #1 does have a knob on the bottom from the spru cut off. So I am going to say they are the same length.

The original sample loads, #1, had to be loaded to .960 or they would not turn or drop out when turned upside down.

#2 my casting seated to .960 would not chamber in the S&W EZ, and would not plunk into or out of the barrel. Yet when then loaded to .970" they would chamber and plunk.

So gun is S&W EZ380. With bullet #1 it would not pass plunk test unless set to .960" COAL. At this lenght bullet and round performed admirably in this gun. Then loaded bullet #2 to same spec and lost all function in this gun. Moved bullet back to .970" and will once again pass the plunk test. Will spin in the barrel and drop.

I have thought about and considered a difference in the alloy as his are range scrap and mine are COWW's. So the thought that his are softer and are swaging down upon seating while mine at that depth are bulging the case enough to prevent seating in the chamber fully. Though this does not explain why one bullet will only chamber when seated to .960" but won't chamber at .970" and the other bullet is the exact opposite.

Again, as-is I cannot measure a difference between the 2 bullets.
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