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Discussion Starter · #1 ·
I have just started casting semiwadcutters in .357 158 grain using a lee mould. The bullet has the microgrooves on it for lubing with the Lee liquid allox. I am now substitutung these bullets for previously purchased 158 grain round nose flat point bullets. Powder type / charge, primers and cases are all the same as before, only the head is changed.
Powder - 4.2 grains of bullseye
Primer - CCI
Case - winchester.
The problem is that some of the bullets are tumbling in flight, hitting the target side on! Can anyone explain why this is happening? 5 out of a batch of 30 tumbled.
This never happened with the round nose bullets which were exactly the same weight.
The alloy I am using to cast is the same as I use for my 148grain wadcutters with no problems.
Any ideas?
 

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Are the bullets fully formed (no voids, defects, etc.) with small to no sprue material left on the base? Also, cast bullets may sometimes have undetectable interior bubbles that show up on target. If the bullets look good, you might try 3.5 gr. of Unique in place of Bullseye, that midrange load seems to work fine with my .357 cast bullets. Hope you find a cure.
 

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Discussion Starter · #3 ·
The bullets are cleanly cast with no damage or sprue on the base. I leave a good size puddle of alloy on top of the sprue plate and get a good neat cut off at the bullet base. The same alloy used on the same day for other bullets seems absolutely fine.
 

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Have you slugged your barrel and checked the diameter of the bullets. I have one revolver that does not shoot the Lee Tumble lube wadcutter either and it is due to an over size bore. I too tend to get better accuracy out of Unique than Bullseye. I also use a lot of HP38 with these bullets with good results.
 

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It sounds like the tumble lube bullets may not be the right diameter. Measure the bullets that are not tumbleing and the tumble lube ones. I'll bet the tumble lube bullets are a smaller diameter.

Sixgun
 

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Bullet is undersized is my guess. If not from casting to small, then a problem with the dies on seating or crimping. Load a bullet, then pull it, is it still the same diameter as loaded?
 

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Have you slugged your barrel and checked the diameter of the bullets. I have one revolver that does not shoot the Lee Tumble lube wadcutter either and it is due to an over size bore. I too tend to get better accuracy out of Unique than Bullseye. I also use a lot of HP38 with these bullets with good results.
The key to clean shooting accurate boolits is proper boolit fit. Slug your barrel and use boolits .001" or .002" larger than bore diameter.
 

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Discussion Starter · #9 ·
tumbling tumble lube bullets

Thanks to everyone for the suggestions.

I am firing the bullets through a Taurus revolver with a 12 inch barrel.

I checked the unsized bullets in the bore and they were oversized. So I sized them to .357 using a lymen sizer die and then relubed them in the same lee liquid allox, hoping this would solve the problem.

BUT - the bullets still tumble even though they were sized down. According to LEE the bullets should have been coming out of the moulds at .357, but they were actually .363, hence the need to size them.

I have tried the reduced charges as suggested, but still tumbling?

Any more ideas?
 

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The next thing to check out is the forcing cone on your revolver. I haven't had this problem in a long time but if I remember right, the bullet needs to be big enough to not fall through your cylinder and also about a thousandth larger than the forcing cone. After it gets through the forcing cone it still needs to be big enough to grab the rifleing. Mike Ventiro is the guy who knows exactly how all of this works and has gon through it all in some of his articles.
Sixgun
 

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Your bullets might be skidding as they leave the muzzle. Try a harder alloy & size to .358" Or try a different load. In 357mag. load 13.0gr of alliant 2400 with you 158gr. Most 38's dont make a round hole, they enter the backer a little crooked. But you did say yours are hitting fully sideways.
According to LEE the bullets should have been coming out of the moulds at .357, but they were actually .363,
This is a lot to be sizing down (.006"), it may be your problem. Lyman said not to size down more than .003" as accuracy could be affected. Make sure you mold is closing completly and nothing is on the face of the mould.
Mold diameter tolerance

Our bullet mold tolerance is stated diameter, +.003/-.000 inch. We gauge our bullet molds with a "go/nogo" gauge, which tends to result in bullet molds that run on the high side of the tolerance. You could probably use one of our standard molds at as-cast diameter with good results.

If the bullets are oversize or out of round the mold is not fully closing. A build up of lube, splash of lead, or a burr on the mold block faces are holding them apart. Inspect the mold block faces and carefully remove anything that might hold the mold apart. Make sure to lubricate the locating pins with solid alox/beeswax bullet lube, Lee part number 90007. If these steps are followed the bullets will cast dimensionally correct.
http://www.leeprecision.com/cgi/faq/index.cgi If you cant correct the diameter the bullets are droping out of the mould at, i would return the mould for a replacement.
 

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Why Lee Bullets Tumble

When a bevel base bullet is oversize by .006" it is sized down by the barrel or die. This sizing deforms the base of the bullet. As the bullet exits the muzzle its base is no longer square to the muzzle. This lets gas escape on one side of the bullet as the other side is still in contact with the muzzle. The bullet becomes unstable and tumbles.
 

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What is the bore dia. of your Tarus? .357" may be too small. Slug it and be sure! Just curious, how did you check your cast in the bore? Just trying to push a bullet into the muzzle doesn't tell you much...
 

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Discussion Starter · #15 ·
I drove a pure lead bullet into the bore of the revolver at the muzzle and measure the width at the grooves and lands. I repeated this at the cylinder end of the barrel. Not totally accurate but as good as I could get. measurements were .355 and .350 respectively. so fit on a .357 sized bullet should be good.
Has anyone checked the temperature of their alloy in a Lee production pot IV ? I assumed temperature range would be around 650 to 750 degrees fahrenheit, which seems to be the recomended temerature range for casting.
I did some checks to see if casting temperature was causing the problem of bullets tumbling. At the lowest setting my pot reaches 712 degrees, 842 degrees at setting 2, and is off the scale of my thermometer at setting 4. This seems very high. My pot is the 240 volt version for use here in the UK. I was casting at the mid point on the thermostat settings, between 3 and 4, so probably casting much too hot.
 

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Thanks to everyone for the suggestions.

I am firing the bullets through a Taurus revolver with a 12 inch barrel.

I checked the unsized bullets in the bore and they were oversized. So I sized them to .357 using a lymen sizer die and then relubed them in the same lee liquid allox, hoping this would solve the problem.

BUT - the bullets still tumble even though they were sized down. According to LEE the bullets should have been coming out of the moulds at .357, but they were actually .363, hence the need to size them.

I have tried the reduced charges as suggested, but still tumbling?

Any more ideas?
According to my Lee Catalog that mold is listed as casting a bullet .358 in diameter which is what all of their molds for that caliber are listed at. What are you using for a casting alloy. I use wheel weight alloy and all of my Lee molds in that caliber cast them right at the .358 or a little above. That diameter is usually fine for most revolvers. I would say sizing down to .357 would be too small for most applications.
Cary
 

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I have found out that Lee molds do not require sizing and shoot great as they cast.
My 17 molds from lee so far have no problems.
Only tumbling problem I had was with the 255RF 45 shot thur my taurus judge.
Even factory lead tumbled. Belive it's was due to not haveing enough speed, since jacked bullets work fine.
 

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Discussion Starter · #18 ·
I have been in contact with LEE and we have identified a problem with the melting pot, seems like I have been casting at temperatures near to the melting point of Aluminum, due to a faulty thermostat. I think maybe at those temperatures the alloy has been overheated and may not therefore be casting right.
Lee customer services if really good, far better than you can expect from any UK based companies, you really have it good in the USA.
Lee have identified the probelm and new thermostat is on the way. Hopefully stable bullets will then be produced.
 
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