Bullet alloy temps and size/wt of bullets

[milprileb]

So there it sits: my RCBS temp gauge and I got no idea if I use it, what its going to do for me.

Is there a temp for pure WW that yields smaller, correct or larger sized bullets dropped from a mold ?

Is there a temp for same results from lead to ww alloy ?

Its time I graduated to using this temp gauge but is t his going to be discovery learning for results?

I just usually back the temp of pot down a tad if bullets start to look frosty. That seems to be okay or 9mm and 45acp bullets but I am about to go up to 30 caliber rifle bullets and here is where deviations in bullets really show up at longer ranges.

Thank you in advance for any input

[geargnasher]

Ok, first you need to unlearn something. Alloy temperature has no effect on whether the boolits are frosty or shiny. Alloy composition (it needs antimony to be frosty) and MOULD TEMPERATURE are what create that effect. You can cast super-frosty, sandblasted boolits from 650 degree wheel weight metal if the mould is hot enough. You can cast wrinkled, shiny, round-edged culls from the same metal at 850 degrees if the mould is too cool.

Hotter alloy will make smaller boolits most of the time (mould temp being equal), because the hot alloy is less dense than cool alloy when poured into the mould, and shrinks more when cooling to a solid state.

That being said, here's my advice on how to use your new tool, and you'll see why I'm not responding to your three main questions directly, except #3 and that is that this isn't complicated, so don't worry!!: Use your thermometer to determine the temperature at which your alloy is FULLY liquid, i.e. no more slush, mush, or unmelted grains in it, and then turn the pot off and let the metal freeze. Watch the thermometer as the alloy cools to a complete solid. Note the temperature of both the full-liquidus, and full solidus points. That will give you a good idea of your alloy composition. Now, when you are ready to cast, let the pot heat until you get to full-liquidus again, verify the temperature, and let the pot continue to heat until the metal is 100 degrees hotter. Take a sharpie and put a mark at 100 over full liquidus, and adjust the thermostat until it stays there. NOW DON'T SCREW WITH IT. Just check the thermometer every few minutes to make sure the alloy is staying within 10-15 degrees either way of that temperature, and only adjust if necessary. You're done. Get to casting, because the rest of boolit casting has to do with pouring technique, mould prep, and MOULD and sprue plate temperature.

Mould temperature is controlled after initial preheating (if any) by casting pace. Most of the time I find it necessary to run between two and four pours a minute, with aluminum and brass, usually four, with some small-block steel moulds and large cavities, two is max or I need a fan. Sprue plate temperature is controlled by the size of the puddle you pour, a fan, or how soon you open the plate. You can preheat your moulds on a hotplate, or with two-cavity moulds you can dip a corner int he melt for 30 seconds or until the lead won't stick to it anymore, do the same with the tab on the sprue plate, and it should save you a lot of warm-up pours.

Once you start, don't stop. Pausing for even twenty seconds in a session can drop 20 or 30 degrees off of the mould temp, and your next few casts will be different than the last few. If you have to stop for a minute to adjust something, make the next three or four pours as quickly as you can to get the mould to catch back up on temp, cull these pours, and then resume as normal. This is always a good habit to learn, because while you may not notice the benefit of consistent boolits with pistol stuff, you will when you cast for long range rifle or if you water-quench your boolits. When water-quenching, a ruthlessly consistent cadence is mandatory for consistent hardness.

A cheap, large-face analog wall clock with a second hand put right over your casting pot is as important at first as a thermometer. Timing is absolutely key to consistency. Cull anything that falls outside the normal cadence, regardless of how it looks.

Gear

[nanuk]

I suggest that this is the type of info that needs to be stickied.

thanks Gear. that made so much sense, and easily digested

[303Guy]

I suggest that this is the type of info that needs to be stickied.

thanks Gear. that made so much sense, and easily digested
I'll second nanuk. Even I could understand it! Thanks Gear. Maybe it's time I took my thermocouple probe and built a power regulator for my pot. All I do is measure and forget!:mrgreen: I found a pair of SCR's I could use. Otherwise I just leave my hot plate on high.

[ColColt]

milprileb-You're very fortunate to be getting this kind of advice and instruction. It took me over 35 years to get it. I would have given my weight in pure lead(thought I was going to say gold didn't you?) to have received info like this when I started and even years afterwards. Consider it apples of gold in pitchers of silver and heed this advice and you'll be a happy camper.

[milprileb]

I could not be more appreciative for all this great advice. Light years of experience shared is a gold mine of knowledge !

I have been pouring all over the pages of this forum and asking questions to clarify the wisdom written down. ITs been rewarding as all get out !

[geargnasher]

This information isn't new or difficult to find, it's been published for years in several of the more popular bullet casting manuals. Condensing and refining the information for practical use may be the challenge, I know it was for me. The conversational format of this forum often makes certain established concepts easier to understand, I think that's why since joining I've gotten so much more value out of the published information that I've been reading since I started casting nearly 20 years ago. That, and some of the people here take the hobby to levels far beyond anything you'll find published in any book.

Gear

[milprileb]

People whose desire is to shoot more and shoot better are the best company to be around.

Folks who cast don't do it for the ambiance of smelting !

[soldierbilly1]

Great info here!
Gear: four pours a minute ... this is really hustling or am I missing something here? how many cavities per mold is this? I ask as this is really quick! thanks for your patience!
billy

[geargnasher]

Many of my Lee two-bangers like to be run that fast, or I should say I like the results I get when I run them that fast, and run as cool an alloy as possible, usually 80-100 degrees over the full-liquidus point.

I have several Lee six-cavity moulds and they generally do ok at about three pours a minute, which is about as fast as practical in most cases, seems that always at least one boolit sticks. If they never stuck, I could run them a bit faster, but really no need. I compensate if necessary by going another 20 degrees hotter on pot temp.

Four-cavity steel moulds are a bear to get hot, then they seem to never cool off, so it's a hustle for the first five or six pours after a good preheat, then slow down before the frosting gets too bad. A small fan helps so the pace can be maintained at two or two-and-a-half pours a minute generally.

I have several brass moulds with heavy blocks, and it seems I can't cast fast enough with them. I can manage a comfortable four pours a minute for an hour or so, but it's tiring.

Once you get the hang of things, efficiency of motion is developed with your routine, and you can just glide through the motions over and over with great speed, or whatever speed is necessary to maintain your mould at the temp it seems to like best with the alloy you're using and the weather conditions. Some key factors are a properly adjusted, tuned, and lubricated mould, having an ergonomic and comfortable casting arrangement, and having confidence in what you're doing. All this comes from experience.

Gear

[sagamore-one]

After reading this thread I am thoroughly convinced I've been spoiled by 35 plus years of casting at 850 degrees with fresh linotype and 6, 8, and 10 cavity Hensley & Gibbs moulds. I was absolutely convinced that it was impossible to cast a BAD boolit. Then the fresh lino dried up and I was forced to blend my own Lyman # 2 alloy which is what I have used for the last 10 years with decent results. Now that wheel weights are getting scarce and the obtainable scrap is of questionable quality and I find myself scratching my head looking for answers. My hat is off to you guys who can cast good boolits at 7oo degrees with aluminum moulds and scrounged alloy.
Like I said.....
I been spoiled..... spoiled bad!

[Land Owner]

After a quarter of a year of casting I have learned that hot alloy and a warming mould will create wrinkled 2nd's almost every cast (5 a minute or more) with two of seven of my moulds. The worst being the Lyman single cavity 180 grain 45 ACP hollow point, which requires significantly more warming of the external void-producing insert prior to commencement of "acceptable" casts. I am remelting from 50 to 100 of the initial casts in order to achieve unwrinkled casts and I am significantly pre-warming the mould with insert. It is frustrating. I will shoot some of my lesser wrinkled boolits, but getting to that moment when the mould, alloy and unwrinkled cast boolit is achieved has been hard to earn.

[gray wolf]

My hat is off to you guys who can cast good boolits at 7oo degrees with aluminum moulds and scrounged alloy.

It can be done and I do it routinely, Lee 2 cavity 175 grain 40 S&W.
Range scrap and COWW + a tiny bit of tin. Liquid at 550* and casting at 650-675*
It's all in the mold Temp. and maintaining the mold temp, Mold temp is achieved with the casting cadence.
If you cast at a slower pace then naturally you need a hotter melt temp.
I don't think it would be possible for me to cast 3 or 4 pours a Min. even with a 4 hole mold if I had the temps 800 or 850*. The mold would get much to hot for me, + I don't think it's best for my tin.
But that's what works for me. It was presented here, I read it, made sense,
I tried it and it works.

[geargnasher]

The more I read the more I'm amazed at the number of people who cast one, maybe two pours a minute with a gang mould, cutting cold, hard sprues with a mallet and running their pots wide open. I was never able to get it to work that way, it's so easy to get the mould nice and hot on a hotplate, pick up the pace, turn the pot down to 100 degrees over full liquidus, and roll out nice boolits from ANY alloy. Pure lead takes higher mould and pot temperture, but same idea.

If you run Linotype at 850 degrees and don't keep it fluxed/reduced constantly, you'll have wheel weight alloy in about four skimmings.

Gear

[milprileb]

Gear,

Not to move too much off the line of discussion but 4 skimmings per pot comment confuses me. I got a ten pot Saeco bottom pour , Once ingots are melted, I magnaflux (will got o sawdust shortly) and leave that black scum on top and pour bullets till I am 80% through the melt in the pot, then skim off black scum and add more ingots and magnaflux again when melted and continue on.

Do you in fact flux and skim 4 times during one pot full of melt ?

[44man]

I'll second nanuk. Even I could understand it! Thanks Gear. Maybe it's time I took my thermocouple probe and built a power regulator for my pot. All I do is measure and forget!:mrgreen: I found a pair of SCR's I could use. Otherwise I just leave my hot plate on high.
If you get something worked out you need to put plans here.
Everything I built eventually burned up, one worked about a year but even with a huge heat sink, it failed.
One other thing about mold heat is that when it gets too hot, the cavities shrink and make smaller boolits.
Once in a while a cherry is not large enough so I get the mold good and hot, put the cherry in and turn it by hand with a wrench.
Amazing how much more metal it removes.

[onesonek]

milprileb,,,,I read that as meaning, if one runs a hot pot, nearly 2-300 degrees over liguidous, Tin oxidizes at a much faster rate. And if it isn't fluxed/reduced back into the melt, then a simple skimming off of the dross is done, you deplete your Tin.
Before I had a full understanding of the process, I just jumped in and started casting. With my first 100 lb's through the pot, I melted down the dross and recovered 4lbs over of alloy, which likely in the greater part, Tin.
Now I follow Gear's and a few other's suggestions on pot temp, pouring technique, and fluxing. In doing this, the level of skimmings/dross , was nearly eliminated to next to nothing, as far as usable alloy is concerned.

[btroj]

One of the big things Gear mentioned was finding a temp and rhythm that works for each particular mould. Mould material, number of cavities, and bullet weight all make each mould an individual. Keeping mound temp in the right window is they key. Find the casting tempo that does that and you will have many, many good bullets.

[kelbro]

I have great results with Gear's method but with 2-cavity iron molds, I get maybe three per minute.

[geargnasher]

Gear,

Not to move too much off the line of discussion but 4 skimmings per pot comment confuses me. I got a ten pot Saeco bottom pour , Once ingots are melted, I magnaflux (will got o sawdust shortly) and leave that black scum on top and pour bullets till I am 80% through the melt in the pot, then skim off black scum and add more ingots and magnaflux again when melted and continue on.

Do you in fact flux and skim 4 times during one pot full of melt ?

Magnaflux??? Who told you to use that? Are you using the flourescent wet die or the try magnetic particle stuff?

To answer your question, what I was talking about when I said you can turn linotype into wheel weights at 850 degrees in about four skimmings is that the tin and antimony (bonded intermetallically as Sb/Sn) oxidize very rapidly on the melt's surface at temperatures over 725-750 degrees. If you keep skimming off this oxide scum layer and don't "reduce" the oxides back into their un-oxidized metallic state so they can dissolve back into the melt, you lose them. So your 12%Sb/4%Sn/84%lead alloy becomes, say, 11%Sb/3.5%Sn/85.5% lead after the first good skimming. Do this a few more times, 10 minutes apart, and you'll have 3%Sb/.5%sn/96.5%Pb before you know it, and a pile of high tin/antimony dross with a small percentage of lead oxide in it.

The lower your pot temperature, the lower the rate of surface oxidation. And if you reduce the oxides before skimming, so you only skim ash and not tin/antimony oxide, none of the precious metals will be lost from the melt.

I only reduce/flux/skim at the beginning of a session, and after each time I stop to add sprues/ingots to refill the pot. Sometimes I leave the sawdust on top and forget about it, it doen't hurt anything. Obviously, if I'm ladling, I have to keep reducing and skimming every few minutes, but often just a stir and scrape with a wooden stick for a minute takes care of the oxides,especially if the pot temperature is kept as low as possible.

The other thing about overheating linotype that really gets me, is that 850 degrees, for example, is too hot for all but pure lead, and a bit hot in my book even for that. I keep harping on 100 degrees over full-liquidus as a good starting point for determining ideal pot temp for your particular mould and circumstances because different alloys have different liquidus points.

Linotype is technically eutectic, if the concentrations are PERFECT, and it has no mush phase, but is fully molten at about 484 degrees if memory serves me correctly. So an ideal casting temperature should be 584 degrees, and in fact it casts so well that often less is needed, it casts just wonderfully at 550 degrees. Heating it two or three hundred degrees higher is insanity from a metallurgist's point of view. Most clip-on wheel weight alloy comes fully out of it's mush phase somewhere between 550-580 degrees depending on the compositions I've messed with. A pot temperature of 625-675 usually does it for me, sometimes I have to go to 700 and add a pinch of tin to get my brass moulds to casting well.
Pure lead melts at 621 degrees, and if you're casting Minies, conicals, or keyed slugs from pure, 750-800 degrees is often in order, because pure lead doesn't want to fill the corners unless the mould and metal are both super hot.

Now I'm still confused about the Magnuflux. Unless there's some boolit metal fluxing compound I haven't heard of with the same name, I assure you what you're using is no good for flux.

Gear

[milprileb]

MARVELUX : its sold by Brownells . I got the name wrong so my mistake. I don't like it much at all. Cruds up the pot with hard black crusty stuff. I got sawdust for next casting session

[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]

From what I can tell, via testing a hot pot with WW, there is no oxidation and loss of tin or antimony even at 1,000 degrees for several hours. Not that can be measured by a hardness tester, gun or target.

I wish there was, but getting the tin & antimony out of alloy is apparently pretty difficult. In any amount that is significant.

Try it out and see what your results are.

I also get bigger bullets with hotter soft alloy (rather than cooler), not smaller. Easy enough to test out too.

There may be reasons to not cast hot, but these aren't them. There also may not be any reasons, I haven't found any yet.

I get the biggest bullets with a hot mould and hot alloy. From WW alloy to soft binary alloy.