Impact of alloy temperate and mould temperate on bullet diameter

[357shooter]

A 145-SWC mould was confounding me quite a bit as the diameters are too small. After a bunch of churn I decided to run a more structured test. The results are different than expected, but look for yourself, and try testing for your caliber. I cast for 357/38 only, FYI.

There a full writeup at http://357shooter.blogspot.com/ is you want all the details.

Using a Lee Pro bottom pour pot, I set the temp on a number. Let the temp stabilize (cycle off), and cast several bullets from just one cavity. Then turned the pot up to the next number and repeated.

Below is a chart of the resulting bullet diameters, all from the same cavity.

Result: Maximum heat is good for the alloy, heat management is key for the mould. If the mould is not hot enough or if it's too hot the bullets are undersized.

http://i878.photobucket.com/albums/ab341/prgallo/Pottempchart.png

[onesonek]

Result: Maximum heat is good for the alloy, heat management is key for the mould. If the mould is not hot enough or if it's too hot the bullets are undersized.




Seems to me this is forcing the mold to expand more than normal????
I disagree with the Max heat part. I agree with the rest in the above.
From what I gather the higher the alloy temp., the more oxidation occurs, requiring more fluxing. I run my pot about 4.5-5 on the scale at just under 700*
685* seems to be what my alloy and mold likes according to my thermometer.
This helps keep the oxidation/dross and fluxing at a minimum. Mold temp is sensitive. Also if you mold is not throwing at somewhat normal temps ( normal being the average of extremes), then it seems your mold is too small, and needs to be dealt with.

[357shooter]

Seems to me this is forcing the mold to expand more than normal????
I disagree with the Max heat part. I agree with the rest in the above.
From what I gather the higher the alloy temp., the more oxidation occurs, requiring more fluxing. I run my pot about 4.5-5 on the scale at just under 700*
685* seems to be what my alloy and mold likes according to my thermometer.
This helps keep the oxidation/dross and fluxing at a minimum. Mold temp is sensitive. Also if you mold is not throwing at somewhat normal temps ( normal being the average of extremes), then it seems your mold is too small, and needs to be dealt with.Disagreement is good. However the data and test results are what they are. The max heat produced the largest diameter bullets, maybe I should have stated it that way. Maybe the mould is small, but it's working out pretty well right now. It's working very well on other moulds too.

[HeavyMetal]

seems to me I've had the same experience over the years with pot temp as the OP has had.

Tired running in the 600's and all I got for my trouble was boolits that were not filled out well.

Never understood how everyone else got good boolits at these temps until I tried to teach one of the BIL's how to cast.

Came home one day to find a nice pile of shiney 45 boolits cooling on my casting table. Mine are usually a little frosted and, when asked, the BIL says he thought the pot was to high and turned it down then boolits came out beautiful!

Uh-huh!

A quick visual inspection did not find one passable boolit in the bunch! Holding a handful under a lighted magnifiyng glass showed incomplete fillout of base's & bands.

Realized that the BIL could not see this until I cranked out the big glass! Once he saw what I wanted the issue went away and the pot's still runs about 730 to give me what I want when I want.

Now I also realize that alloy content can play a huge part in useful pot temp and alloy's like Linotype and Lyman number two can be run at much lower temps and get good fillout because of the Tin content.

Because of plain old cost I do not run very high Tin content alloy which means a bit higher pot temp.

So, as in all things, the circumstance of the situation deterimines the correct pot temp every time you fire it up.

[BABore]

You are making a mistake of confusing alloy/pot temperature with the boolit size. More correctly, it should be mold temperature verses boolit size. Yes, the alloy needs to be at a high enough temperature to flow correctly. But, it is the mold that must be run hot enough for good fillout and thus max boolit size. Some get there by just running the alloy hotter. IMO this is the wrong way to correct the issue. Proper casting cadence and mold block temperature maintanence produces the same end results without the high temperature effects on the alloy.

In your test you were also skewing the results by only pouring one cavity. The mold blocks were not seeing the same amount of heat input as they would normally. Also, on molds with poor venting, the first cavity poured will usually fill out better than the last one.

[MiHec]

You are making a mistake of confusing alloy/pot temperature with the boolit size. More correctly, it should be mold temperature verses boolit size. Yes, the alloy needs to be at a high enough temperature to flow correctly. But, it is the mold that must be run hot enough for good fillout and thus max boolit size. Some get there by just running the alloy hotter. IMO this is the wrong way to correct the issue. Proper casting cadence and mold block temperature maintanence produces the same end results without the high temperature effects on the alloy.

In your test you were also skewing the results by only pouring one cavity. The mold blocks were not seeing the same amount of heat input as they would normally. Also, on molds with poor venting, the first cavity poured will usually fill out better than the last one.



Another one with same thinking

[John Boy]

A 145-SWC mould was confounding me quite a bit as the diameters are too small. 357, if you want diameters that are within the specifications of the mould, bring the temperatures up to the degree where the sprue puddle frosts in 5 seconds for revolver bullets. For rifle bullets in the 500+ gr range ... 8 to 10 seconds for the puddle to frost

Believe it or not, one doesn't even have to use a thermometer as long as the temperature is held constant to produce the seconds for the puddle to frost. Plus the bullets will drop within a 1gr or less weight variance

[45 2.1]

You are making a mistake of confusing alloy/pot temperature with the boolit size. More correctly, it should be mold temperature verses boolit size. Yes, the alloy needs to be at a high enough temperature to flow correctly. But, it is the mold that must be run hot enough for good fillout and thus max boolit size. Some get there by just running the alloy hotter. IMO this is the wrong way to correct the issue. Proper casting cadence and mold block temperature maintanence produces the same end results without the high temperature effects on the alloy.

In your test you were also skewing the results by only pouring one cavity. The mold blocks were not seeing the same amount of heat input as they would normally. Also, on molds with poor venting, the first cavity poured will usually fill out better than the last one.


Another one with same thinking

+2 to the above


Believe it or not, one doesn't even have to use a thermometer as long as the mold temperature is held constant to produce the 5 is preferable seconds for the puddle to frost. Plus the bullets will drop within a 1gr or less weight variance

Weight variance for a 45 cal. 500 gr or so boolit can be held to 0.1 gr or less with proper technique. believe it or not. That is a measure of SKILL in the ART of boolit casting.

[SwedeNelson]

It would be very interesting to send out a single 5 cavity mould to 25 or 30 different
casters and have them send back a sample of what they cast.
Maybe list alloy, mould temp. and pot temp.

My meager testing has shown that mould block temp. is probable the single most
important factor in getting consistent casting.

But I have done very little work with trying to increase or decrease size.

Good write up 357shooter

Swede Nelson

[kbstenberg]

As stated before. More knowledge here by accident than most places by intent!!!
To you all I tip my hat.:smile::smile:
Kevin

[kelbro]

A steady cadence + steady alloy temp produces the most consistent weight boolits for me. I have not tried measuring them but the amount of force when sizing also seems consistent when the weights are all within +/-1%. This is the same with all of the alloys that I use. Pb, WW, 50/50 Pb-WW, and #2.

As if weighing wasn't enough, now you have me wanting to measure boolits! I have a few molds that throw very consistent boolits but a couple definitely have slight cavity to cavity variations in size.

[BABore]

Mold temperature and the resulting boolit size is affected by alloy, alloy temperature, casting cadence, and ambient temperature. Boolit weight variance is affected by size, air pockets, and inclusions. Because of this, simply weighing boolits is utterly useless unless you can effectively manage and control the variables or measure each boolit prior to weight sorting them. Otherwise, a small sized boolit that has no internal voids can weigh the same as a larger boolit with air pockets.

45 2.1 is correct in that it is not hard to cast 400-500 grain boolits with +/- 0.1 grains of variance. It just takes alot of practice. Having a tight control over weight variance is not necessary if we're just talking about a perfect, homogenous solid. Cast boolits are by no means perfectly solid but rather loaded with pinholes and air pockets that cause inbalance. Running boolit weight variance of +/- 1.0 grains or more is caused by either poor mold temp. management or casting technique.

[NVScouter]

I was pondering this over the weekend and ask here...but here it is!

Great info.

357 are the numbers at the bottom the sequence of boolits or just part of the spread sheet? Also you say you let the mould warm up, did you do this buy casting 20 or so boolits before starting for test?

Swede send me one of those nice .357 190g moulds and I'll test the heck out of it :kidding:

[warf73]

357 I did the same thing with my Lee 476-400-RF, the alloy temp at 725~750 with a heated mold the boolits drop .476~.477". As I add heat all the way up to 1000* alloy temp the boolits kept growing but stopped at 478~.479". My alloy was straight WW nothing else added. During this test all I did was make 10 boolits then add more heat till I reached 1000*.

I can say with my normal alloy temp 725~750 my boolits very from 495~496grs once I get good fill out (which is normaly 3~6 pours). My pouring tempo is normaly 2~3 pours per min nothing stressfull just easy going.

If you really need to drop a bigger boolit I suggest beagling it vs. adding heat up to 1000* but to each there own.

[geargnasher]

You are making a mistake of confusing alloy/pot temperature with the boolit size. More correctly, it should be mold temperature verses boolit size. Yes, the alloy needs to be at a high enough temperature to flow correctly. But, it is the mold that must be run hot enough for good fillout and thus max boolit size. Some get there by just running the alloy hotter. IMO this is the wrong way to correct the issue. Proper casting cadence and mold block temperature maintanence produces the same end results without the high temperature effects on the alloy.

In your test you were also skewing the results by only pouring one cavity. The mold blocks were not seeing the same amount of heat input as they would normally. Also, on molds with poor venting, the first cavity poured will usually fill out better than the last one.

+3. This has been my experience as well, and I think I've made every wrong move possible with alloy and mold temp to finally figure out what works best for me. Simply put, the requirements for the "most ideal" temperature of the alloy are dictated by the composition and physical properies of the alloy itself (and are constant and predictable), and the quality of the boolit itself is dependent on mould block and sprue plate temperature combined with casting technique and general method; here each mould is completely unique in this regard.


It would be very interesting to send out a single 5 cavity mould to 25 or 30 different
casters and have them send back a sample of what they cast.
Maybe list alloy, mould temp. and pot temp.

My meager testing has shown that mould block temp. is probable the single most
important factor in getting consistent casting.

But I have done very little work with trying to increase or decrease size.

Good write up 357shooter

Swede Nelson

Another point to ponder is my repeated observation that air-cooled boolits cast from a hotter mould, i.e. at the medium frosty point with WW or similar alloy, will be significantly harder than a boolit cast from the same mould and same pot temperature but with a cooler mould that is dropping shiny boolits. For example, I ran a batch of Lee 457-340 single-cavity boolits at 710 pot temp with clip-on alloy with the mould at 420 degrees, then slowed down until I got to 325 and once I got it steady kept a long run of those. After two weeks the cooler ones were at 11.4 BHN and the hot, frosty ones were at 14.8. The frosty ones were, on average, .0004" smaller than the ones cast from the cooler mould. Seen the trend many times but this is the only time I really measured temps closely to see.

Gear

[357shooter]

You are making a mistake of confusing alloy/pot temperature with the boolit size. More correctly, it should be mold temperature verses boolit size. Yes, the alloy needs to be at a high enough temperature to flow correctly. But, it is the mold that must be run hot enough for good fillout and thus max boolit size. Some get there by just running the alloy hotter. IMO this is the wrong way to correct the issue. Proper casting cadence and mold block temperature maintanence produces the same end results without the high temperature effects on the alloy.

In your test you were also skewing the results by only pouring one cavity. The mold blocks were not seeing the same amount of heat input as they would normally. Also, on molds with poor venting, the first cavity poured will usually fill out better than the last one.
I tested at different alloy temps and different mould temps too. Lower temp alloy always produce smaller bullets. No matter what mould temp is used. Lower mould temps made it even worse.

With the pot on full and fully preheated (some of this info is in the blog and not in the post) and the mould preheated to 360, the bullet diameter is the biggest. Lower either one and the size is affected.

Regarding the results of using 1 cavity, this was the most consistent way to test. When I validated with a full casting session the bullets actually cast even bigger. The results improved.

Managing the mould temp is key, for the first 1/3 pot I cooled the mould every 3 casts (5 seconds on a wet rag, 2 seconds delay), then went to every 2 casts. I decided that based on the look

So a full casting session improved on the test results with many bullets at .360 and .361. A cooler alloy in the pot degraded the results.

[357shooter]

357, if you want diameters that are within the specifications of the mould, bring the temperatures up to the degree where the sprue puddle frosts in 5 seconds for revolver bullets. For rifle bullets in the 500+ gr range ... 8 to 10 seconds for the puddle to frost

Believe it or not, one doesn't even have to use a thermometer as long as the temperature is held constant to produce the seconds for the puddle to frost. Plus the bullets will drop within a 1gr or less weight varianceThanks, that sounds about right. At least with the revolver bullets as I don't cast for rifle.

I think I'm there. What I did different is record the test and then measure the diameter every step along the way.

It's interesting to see how diameter is unpredictable when the mould gets way too hot.

What I forgot to mention is that the roundness improved with the high alloy temp and managing the mould temp.

[243winxb]

Quote:
The bullet diameters and weights presented in this list
are based on the use of Taracorp’s Lawrence Magnum
bullet alloy (2% tin, 6% antimony, 1/4% arsenic,
91.75% lead).
Bullet diameters and weights will vary considerably
depending on the lead casting alloy used. This variation
can be as much as 1/2% on the diameter, and 8% on
the weight among the most commonly used casting
alloys. For example, a .358-158 grain bullet might
show a diameter variation of .002", and a 13 grain difference
in weight.
Of the most commonly used alloys, wheel weights (.5%
tin, 4% antimony, 95% lead) will produce bullets having
the smallest diameter and heaviest weight, with
such bullets running approximately .3% smaller in
diameter and 3% heavier than bullets cast with
Taracorp's metal. Linotype will produce bullets with the
largest diameter and lightest weights. This alloy will
produce bullets approximately 1/10% larger and 3%
lighter than Taracorp. Other alloys of tin and antimony,
with antimony content above 5%, will produce bullets
with diameters and weights falling between those cast
from wheel weights and linotype.
Alloys containing little or no antimony will cast considerably
smaller than wheel weights and in some cases
will produce bullets too small for adequate sizing.
Within the limitations given above, the weight and
diameter of a cast bullet can be adjusted by varying the
alloy’s antimony content.
The size and weight of bullets of a given alloy will also
vary according to casting temperature. Higher temperatures
will result in greater shrinkage as the bullet
cools, thereby producing a slightly smaller and lighter
bullet than one cast of the same alloy at a lower temperature Cast Bullets

[357shooter]

Thanks for the encouragement. I'm always ready to participate in a coordinated test. Figuring this stuff out is fun! I'm kinda thinking it's never ending...



It would be very interesting to send out a single 5 cavity mould to 25 or 30 different
casters and have them send back a sample of what they cast.
Maybe list alloy, mould temp. and pot temp.

My meager testing has shown that mould block temp. is probable the single most
important factor in getting consistent casting.

But I have done very little work with trying to increase or decrease size.

Good write up 357shooter

Swede Nelson

[357shooter]

To clarify the chart: The numbers on the bottom are the first bullet, second bullet, third bullet from the same cavity, with the pot constant.

The colored lines are one pot setting with 7, 8 and 9 the same preheated mould temp. The 9.5 is with a hotter preheated mould (360) and represents the best result.

I also tested other pot temps with the mould preheated to 360 and they are smaller.

I agree the correct mould temp and mould temp management has the biggest effect on size.

Second to that is alloy temp, and hotter is better.

When both are "right", it works best. There is a bit of a synergy that gets the most out of a mould.

When all was said and done I did a full casting session (the steps, detailing how the mould temp was controlled, and goes to the pace of casting) and the results from that were BETTER then the chart indicates. So yes, using a single cavity skewed the results, but not to the good.

[357shooter]

Gear:

The hot mould you mention that cast smaller bullets can be seen in the graph. The mould is getting hotter each time another bullet is cast. They get bigger to a point, then start getting smaller as they start to get frosty.

When managing the temp during the full final casting session, noticing early signs of frosting is what cause me to start cooling the mould every 2 casts instead of 3. It worked out well as I never got to far down the slope of getting smaller.

[357shooter]

Mold temperature and the resulting boolit size is affected by alloy, alloy temperature, casting cadence, and ambient temperature. Boolit weight variance is affected by size, air pockets, and inclusions. Because of this, simply weighing boolits is utterly useless unless you can effectively manage and control the variables or measure each boolit prior to weight sorting them. Otherwise, a small sized boolit that has no internal voids can weigh the same as a larger boolit with air pockets.

45 2.1 is correct in that it is not hard to cast 400-500 grain boolits with +/- 0.1 grains of variance. It just takes alot of practice. Having a tight control over weight variance is not necessary if we're just talking about a perfect, homogenous solid. Cast boolits are by no means perfectly solid but rather loaded with pinholes and air pockets that cause inbalance. Running boolit weight variance of +/- 1.0 grains or more is caused by either poor mold temp. management or casting technique.Now that you mention it. Casting with a really hot pot also required closely monitoring and adjusting the rate of flow.

Too slow and wrinkles appear.

Too fast and wrinkles appear.

Getting it right was pretty easy so that is good, also as the alloy is used up a small increase in flow at the first signs of wrinkles keeps everything right.

That's part of the craft of casting, as opposed to the metrics and charts.

Both are important.

[357shooter]

357 I did the same thing with my Lee 476-400-RF, the alloy temp at 725~750 with a heated mold the boolits drop .476~.477". As I add heat all the way up to 1000* alloy temp the boolits kept growing but stopped at 478~.479". My alloy was straight WW nothing else added. During this test all I did was make 10 boolits then add more heat till I reached 1000*.

I can say with my normal alloy temp 725~750 my boolits very from 495~496grs once I get good fill out (which is normaly 3~6 pours). My pouring tempo is normaly 2~3 pours per min nothing stressfull just easy going.

If you really need to drop a bigger boolit I suggest beagling it vs. adding heat up to 1000* but to each there own.
I'm OK with casting the pot on full, as the fill-out is incredible, keeping the flow right is very easy too. The bullets are also very round, that's very nice as well.

I'm not sure I need them much bigger. As I continue to work through the sizing/lubing they are even more round. And growing a bit. An earlier batch of this same alloy has expanded .0006 inches over the first 10 days.

So working out the next steps, in pursuit of less than .5 inch groups at 25 yards, is already well underway.

[357shooter]

A steady cadence + steady alloy temp produces the most consistent weight boolits for me. I have not tried measuring them but the amount of force when sizing also seems consistent when the weights are all within +/-1%. This is the same with all of the alloys that I use. Pb, WW, 50/50 Pb-WW, and #2.

As if weighing wasn't enough, now you have me wanting to measure boolits! I have a few molds that throw very consistent boolits but a couple definitely have slight cavity to cavity variations in size.
Hey kelbro, how's it going?

Yeah, there's always the next thing to try. Using moulds with fewer cavities does add to consistency. Using 3 or 4 cavities of a larger mould has the same effect.

I've had great results with the 200-SWC from a 2 cavity, part of it is due to the perfect match of both cavities. It's also just a great bullet.

[357shooter]

243winxb: The results from these test agree with the alloy being a challenge. My preferred alloy for all 357 magnum loads is 98% lead and 2% solder (more correct than calling it tin). The accuracy in all bullet weights and all powders have proven this to be the most accurate. So I use it as often as I can.

The challenge is that this alloy tends to cast small. That's why I finally did this type of a test.

The fact that hotter produces bigger bullets is in direct conflict with what you posted. All I can say is that I've tried this with other moulds and it keeps working by producing fully sized bullets, with the pot on full. They also grow a bit afterward, they are more round and shoot great.

I tried the cooler alloy approach and it doesn't work.

Added later: I did try casting at 750 degrees, which is 6 on on my pot. The small rounded bullets were so bad I just didn't inlcude them in the results. My point is there were a bunch of additional tests performed to validate the results.

[357shooter]

I hope everyone has a response and thanks for all the great feedback and input.

[geargnasher]

Thanks for posting your results and the blog link, I always enjoy reading other people's tests and results.

Gear

[357shooter]

All the great discussion is thought provoking, a good thing.

The other benefits of casting with a hot pot is information I didn't cover in the post or the Blog. It's important enough to work up the next post. The moulds really do seem to respond well and cast great with a hot pot.

I know there's a bunch of reasons against casting hot, such as cooking out the tin.

However, for me, 9.5 isn't much hotter than what I had determined worked the best anyway. In spite of the warnings to the contrary.

The results of less than 1 inch groups at 25 yards with my Taurus 66 6inch is all with soft lead and casting hot. It was already working best, now I know why and can take it to the next level.

My attempts to cast larger bullets with cooler temps failed, they always got smaller. Now I know that's the way it works. Plus keeping the mould from overheating is critical.

Less than .5 inch groups has proven to be a challenge, that's the next level.

So the results are, to a point, already demonstrated at the range and listed in the top loads. That's all listed down the blog a bit though.

Thanks again everyone.

[onesonek]

Disagreement is good. However the data and test results are what they are. The max heat produced the largest diameter bullets, maybe I should have stated it that way. Maybe the mould is small, but it's working out pretty well right now. It's working very well on other moulds too.

My lack of experience, didn't allow me to state as eloquently as the other's,,,,,from which I learned a great deal. Personally I found running my pot hot, (as I tried once slightly over 800* on setting 7) that I had high weight deviations more than anything,,,and lots of dross. With cooler pot I get a weight runout of .05% and running a cooler mold just enough to get rid of wrinkles, get the diameter I figured on. I'd be tickled if I could get weight down to .01 gr. variance as some state as possible. I just need more time. I am looking to get a thermometer for monitoring mold temp, I'm sure keeping that temp consistant is a great deal. If I run the mold to where the boolits are frosted slightly heavy, they shrink .0013-5" on me. I'd hate to guess what my alloy temp would be if I ran the pot on max setting.

[243winxb]

If you get a Lee aluminum mold super hot, along with the alloy, you will get a larger bullet as the mould expands from the excess heat. About1200 degress if i remember correctly. I could go look it up again, maybe, but i am lazy.

[cajun shooter]

First let me say that I will be +4 with BaBore and others of that group. It is very simple physics to start with in that the hotter the metal the bigger the diameter will be. Heat causes expansion and cold will be just the opposite and shrink. 357 you are on the correct path in that your mind is telling you to discover why things take place. That is much better than one who does nothing and accepts all things that happen. With your Lee pot is your first failure to control your standards as they must be if you wish to show the correct answers. The pot is equipped with a rheostat that will change temperature as each bullet is poured. They will not keep the constant temperature that is needed for such a test. You can see what I'm referring to by using a good thermometer in your pot. I tried to do a similar test about three years ago that ended in me never using another Lee pot. Your second failing was as has been pointed out in that the mold temperature plays a very important part as well. It also has to be in the correct range to make your testing valid. This is in no way meant to demean you as it is given in the form of constructive criticism. I have been pouring bullets since 1970 and still learn from this forum. I have found that if one is pouring bullets to amass a large quantity then you need to pour with more than one identical 2 or more cavity mold. I have also found that if you use a pot that is equipped with a real thermometer that will make life much easier. Then I have also discovered that if you have a good single burner hot plate to rotate the molds from that it helps to keep all your temps in that good range. While pouring bullets with this method you will have good fill out and bullet dropping and very little difference in weight, size or looks. Your reject pile will or should be close to zero.

[handyman25]

Very good post, lots of information to get the mind working. I just purchased a Lee pot. Lapped the valve stem rod and no drips. But the lee pot does have problems. The 500 watt element is too small. A rheostat instead of a thermometer, but these problems can be over come. The price is so low that to me it is worth the extra work. I put in the alloy set the dial to high as it will go and wait. I put extra alloy in a toaster oven ($5 garage sale find) and get it good and hot. Putting cold alloy in pot drops the temp down very fast and then you wait another 20 minutes (element too small) pre heating avoids this. When the alloy gets to 705 degrees I set the dial to 4.5 and start casting when the alloy gets to 708 - 710 I drop in a couple of sprue cuts offs and the temp drops down to 705 and I can contune to cast. For me keeping the alloy temp plus or minus 5 degrees and the mold blocks a uniform temp I get very nice looking bullets with even weights. I have found that the Lee pot will not keep a even temp by its self. I need to slow down my casting speed anyway so my mold will not get too hot. I cannot justify the costs of a RCBS unit, and I think RCBS is very good stuff. I would like to add I have been casting since 1963 and I am still learning almost evey day thanks to this site.

[357shooter]

First let me say that I will be +4 with BaBore and others of that group. It is very simple physics to start with in that the hotter the metal the bigger the diameter will be. Heat causes expansion and cold will be just the opposite and shrink. 357 you are on the correct path in that your mind is telling you to discover why things take place. That is much better than one who does nothing and accepts all things that happen. With your Lee pot is your first failure to control your standards as they must be if you wish to show the correct answers. The pot is equipped with a rheostat that will change temperature as each bullet is poured. They will not keep the constant temperature that is needed for such a test. You can see what I'm referring to by using a good thermometer in your pot. I tried to do a similar test about three years ago that ended in me never using another Lee pot. Your second failing was as has been pointed out in that the mold temperature plays a very important part as well. It also has to be in the correct range to make your testing valid. This is in no way meant to demean you as it is given in the form of constructive criticism. I have been pouring bullets since 1970 and still learn from this forum. I have found that if one is pouring bullets to amass a large quantity then you need to pour with more than one identical 2 or more cavity mold. I have also found that if you use a pot that is equipped with a real thermometer that will make life much easier. Then I have also discovered that if you have a good single burner hot plate to rotate the molds from that it helps to keep all your temps in that good range. While pouring bullets with this method you will have good fill out and bullet dropping and very little difference in weight, size or looks. Your reject pile will or should be close to zero.? I am confused by all your points.

So I said the most important thing is mould temperature, to clarify that means both to start with and then managing the mould temp. I'm guessing with all the posts you missed that key point. It was in a later post and not the OP.

Related to the first "failing" it was, well, a complete success. I had some undersized bullets before testing. Ran the tests by tweaking the controls, measured the results and am now able to get full size great bullets.

What worked was the opposite of what I expected to find though. Many folks insist cooler makes bigger bullets. Not so, with this alloy anyway. Actually with WW and home-brewed Lyman #2 any setting below 8.5 on the pot doesn't work well.

If I remove the big bullet from the graph, it becomes clear that in the other tests the diameter grew with hotter alloy. The big jump in size changes the scale enough to make it seem that the impact was minimal. So I disagree with just the part that implies alloy temp doesn't contribute to bigger bullets. It did, it does. But we don't have to agree.

The reject range so far, in subsequent casting sessions is very close to zero. The sizes are incredibly consistent and they are very round, fillout is excellent.

Hearing about the related failures is a bit confusing in this context. All goals have been achieved and expectations exceeded.

I am looking at the NOE mould thermometer, tightly controlling that can most likely help out even more. It's always good to tweak things a bit more.

Already use the hot plate too.

I'm not trying to argue with you, but I also think these points of disagreement needed to be stated.

P.S. If the mould temp was the only factor, the test with lower mould temps would not have peaked and then produced smaller bullets, as they did. They would have continued to grow in size until heated up to the 360 degrees.