Tin questions

[milprileb]

Seems I got two options if I want to add tin to a ten pound pot of wheel wts (of which has been added 1.5 pounds of pure lead).

a. I can throw in some linotype but I have no idea how much and assume lino has tin in it.

b. I can toss in some no lead solder. How much remains a mystery as my reloading scale reads grains and not ounces.

Would some patient adult please comment so this old idiot can sort out what option will work and if both will work.... how much to put in the pot.

I guess I better get me a scale that reads in ounces ... the boy has one and I am sure he will loan it for this cause.:coffee:

[TCFAN]

Can't help on the tin question but you might look at yard sale or flea markets for a set of old postal scales. They weigh in ounces up to a couple of pounds and at least the one that I have seen to be very accurate. And they don't cost to much....................Terry

[mooman76]

7000 grains per LB and 16 oz per LB. = 437.5 gr. per oz.

[bumpo628]

So, you've got:
8.5 lbs of clip on WW
1.5 lbs of pure lead
and you want to know how much linotype or lead-free solder to add to get the tin up to 2% or so? Or 0.5%, 1% etc?

Without any additives, you should have an alloy close to this with just the WW + Pure:
8.5 lbs WW + 1.5 lbs Pure = alloy with 0.43% tin, 2.55% antimony
That is assuming that WW has 0.5% tin and 3% antimony.

Here are a few ways to bump up the tin with the alloys you have on hand:
8.5 lbs WW + 1.5 lbs Pure + 1 oz LF Solder = alloy with 1.01% tin, 2.53% antimony
8.5 lbs WW + 1.5 lbs Pure + 2 oz LF Solder = alloy with 1.59% tin, 2.52% antimony
8.5 lbs WW + 1.5 lbs Pure + 3 oz LF Solder = alloy with 2.17% tin, 2.50% antimony

8.5 lbs WW + 1.5 lbs Pure + 0.25 lbs Linotype = alloy with 0.51% tin, 2.78% antimony
8.5 lbs WW + 1.5 lbs Pure + 1.00 lbs Linotype = alloy with 0.75% tin, 3.41% antimony
8.5 lbs WW + 1.5 lbs Pure + 2.00 lbs Linotype = alloy with 1.00% tin, 4.13% antimony
8.5 lbs WW + 1.5 lbs Pure + 3.00 lbs Linotype = alloy with 1.25% tin, 4.73% antimony
8.5 lbs WW + 1.5 lbs Pure + 4.25 lbs Linotype = alloy with 1.49% tin, 5.37% antimony
8.5 lbs WW + 1.5 lbs Pure + 5.75 lbs Linotype = alloy with 1.73% tin, 6.00% antimony
The last one is pretty close to hardball.

As mentioned before, 1 oz = 437.5 grains

[Will]

about a 2 inch piece of standard plumbers LF solder weighs about 1/10 ounce.

[462]

Using 2% added tin, which seems to be the concensus amount, equates to .32 ounces per pound of wheel weights. Or, 3.2 ounces per 10-pounds.

I'm in agreement with Will. Whenever I need additional tin, I use a 6-inch section of 95-5 solder per 10-pounds of weights.

[whisler]

If Will's statement is true that 2inches of LF solder=.1 oz., then your 6 inches - .3 oz or enough for 1 lb of melt, not 10 lb. Or did I miss something?

[williamwaco]

A different opinion !

I have been casting handgun and .30 caliber bullets from wheel weights since before 1960.

I used to buy and add tin to the mix because it made them fill out better, or so they said. Then one day I didn't have any and I lived over 100 miles from the nearest source. I melted down about a gallon of wheel weights and tried them anyway just to see how bad they were.

Well - To my surprise, I could tell not difference at all. I have been casting from wheel weights ever since and I have never again spent a dime on tin.

I do occasionally add linotype to wheel weights it adds tin but that is not the reason I do it. I do it to make them harder. A small amount of linotype will harden up wheel weights nicely.

[Mavrick]

What is it in Linotype that makes it harder? Why don't you just add THAT?
Gene

[Jeffrey]

Antimony makes lead alloy harder. It is added as an alloy because antimony has a melting point significantly higher than the melting point of lead. I have heard of microparticulate antimony being used. Lino or chilled shot is a lot easier to deal with, and a lot easier to come by. Antimony alone will lead to leading. Tin must be added too.

[geargnasher]

In a lead solution, antmony and tin will form what is called an intermetallic bond called Sb/Sn, and is roughly 50/50. This intermetallic is responsible for making boolit metal tough as well as hard. Too much antimony and it will be very brittle, any significant antimony without at least a touch of tin has a greater tendency to "lead" the bore. Too much tin, i.e. more than the amount of antimony present, causes it's own problems, but that's another story.

Gear

[462]

If Will's statement is true that 2inches of LF solder=.1 oz., then your 6 inches - .3 oz or enough for 1 lb of melt, not 10 lb. Or did I miss something?

Whistler,
Thank you for pointing out my mistake. I stand corrected.

[geargnasher]

Actually, depending on the needs, that could be plenty.

Gear

[milprileb]

Is this trial and error or is there a major % of tin to alloy for 45acp and 9mm cast bulelts ?

[geargnasher]

It's only as complicated as you want to make it. .45 ACP and 9mm have very different needs.

Gear

[milprileb]

Gear... for 9mm what % tin would you suggest?

[Mavrick]

I find linotype difficult enough to obtain that I'd rather use the elements to add to come to the alloy I'm trying to get.
Now, I can go to Rotometals and get a mixture that is a lot easier to make the combination I seek. Since right now I have enough powdered antimony from LETS and the proper flux, I go directly to the alloy. When that's gone, I'll buy a 'heavy alloy' (heavy in the percentage) and smelt it together, as it's a lot easier when ya don't have the right flux.
I've shot a bit of lino, though it's probably not a good idea if you want the boolit to work in a certain way, ie, expand. It'll probably shatter, first. I use it for high pressure, high velocity stuff, mostly for accuracy...sometimes it works.
As a hard-cast hunting boolit, WW+2%, or Lyman #2 probably work as well as you can expect from a handgun. I use a .41 Magnum.
Have fun,
Gene

[timkelley]

A little OT but I never could find a good used postal scale anywhere at a reasonable price. I looked on line for just postal scales and found new electronic scales at reasonable prices. Mine will weigh one ounce to fifty pounds and while I am sure it is not absolutely precise it is close enough for alloy mixing.

[Cranium]

I've been using range lead for my casting. On average, it is between 10-10.5 BHN and my goal is to have between 11 and 12 BHN for my 9mm boolits.

To achieve this, I add 4.8 oz Tin, 9.6 oz of SuperHard (30% Antimony) to 16 lb of the range lead. Air cooled it gives me the desired range. I haven't tested BHN with quenching yet.

Thumb rules I use:

For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.
Brinell Hardness equation: 8.60 + ( 0.29 * Tin% ) + ( 0.92 * Antimony% )

Example: Lyman #2 (consists of 5% tin and 5% antimony) = 8.6 + (0.29 * 5) + (0.92 * 5) = 14.65 BHN

[bumpo628]

I've been using range lead for my casting. On average, it is between 10-10.5 BHN and my goal is to have between 11 and 12 BHN for my 9mm boolits.

To achieve this, I add 4.8 oz Tin, 9.6 oz of SuperHard (30% Antimony) to 16 lb of the range lead. Air cooled it gives me the desired range. I haven't tested BHN with quenching yet.


That mix should give you about 2% tin, 2% antimony, hardness @ 11 according to my calculations. It all depends on the mix of your range lead of course.

[Cranium]

Yes, that was my goal for percentages and how I derived what to add. Of course the 11 BHN is based on range lead being at around 9.6 BHN and mine is a bit harder. The results from my alloy has been consistently between 11.5 - 12.1 BHN.

[geargnasher]

"For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.
Brinell Hardness equation: 8.60 + ( 0.29 * Tin% ) + ( 0.92 * Antimony% )"

It is virtually impossible to calculate the hardness increase of added tin or antimony, because for one thing it isn't linear, and for another the Sb/Sn intermetallic has it's own rate of increase in hardness, and the amount of Sb/Sn present varies with the proportion of each. For example, the hardness of just lead and tin only hardens with additional tin up to a certain point, but throw in 1% antimony and the hardness increases significantly. Start with 2% antimony, add 2% tin, and you'll find that the .3 bhn per percent might not come out right.

Gear

[Cranium]

"For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.
Brinell Hardness equation: 8.60 + ( 0.29 * Tin% ) + ( 0.92 * Antimony% )"

It is virtually impossible to calculate the hardness increase of added tin or antimony, because for one thing it isn't linear, and for another the Sb/Sn intermetallic has it's own rate of increase in hardness, and the amount of Sb/Sn present varies with the proportion of each. For example, the hardness of just lead and tin only hardens with additional tin up to a certain point, but throw in 1% antimony and the hardness increases significantly. Start with 2% antimony, add 2% tin, and you'll find that the .3 bhn per percent might not come out right.

Gear

While you may be technically correct in the statement that the additions of Sb & Sn in different proportions do not result in a BHN that can be represented by a linear equation, it is still a very good formula to use and is quite adequate for the limited range of hardness used for casting bullets.

A good reference for this type of data that I've learned much from was written, in part, by Glen Fryxell who has a PhD in Chemistry and whose professional interests were in part nanostructured materials and molecular self-assembly. He lays out the foundation
http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m

The equation is also referenced on Rotometals.com (http://www.rotometals.com/Bullet-Casting-Alloys-s/5.htm) and doing a Goggle search will reveal this equation's usage elsewhere as well.

So, while not exact science, it is a good thumb rule. And if you have an alloy tester that is exact enough and repeatable enough to ±.1 BHN (consumer testers are not), you can tweak your alloy a little to get the exact BHN you desire.

For reference, the reason I state that consumer testers are not accurate enough for repeatable, accurate results is based on the study found here: Testing The Consistency Of The Commonly Available
Cast Bullet BHN Test Equipment (http://www.lasc.us/Shay-BHN-Tester-Experiment.htm)

[felix]

Consumer tasters (testers) are used by the liquor business for blending purposes to make a lot "right", i.e., tasting like the one referenced, or for a taste that a probable "consumer" will purchase. Insurance cannot be acquired for those now "professional" testers after 7 years of practice. Thus, new individuals are constantly rotated into a testing panel after training. ... felix

[Cranium]

Consumer tasters (testers) are used by the liquor business for blending purposes to make a lot "right", i.e., tasting like the one referenced, or for a taste that a probable "consumer" will purchase. Insurance cannot be acquired for those now "professional" testers after 7 years of practice. Thus, new individuals are constantly rotated into a testing panel after training. ... felix

LOL....that doesn't surprise me. Have to rotate out the Alcoholics they've created over several years of drinking free for research. ;)

[XWrench3]

i agree with Maveric, lino is getting hard to find. at least lino that is still in type form. which is the only kind i will buy (unless from rotometals). if it isn't in type form, you have no idea what you are buying.

[ColColt]

I've been using range lead for my casting. On average, it is between 10-10.5 BHN and my goal is to have between 11 and 12 BHN for my 9mm boolits.

To achieve this, I add 4.8 oz Tin, 9.6 oz of SuperHard (30% Antimony) to 16 lb of the range lead. Air cooled it gives me the desired range. I haven't tested BHN with quenching yet.

Thumb rules I use:

For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.
Brinell Hardness equation: 8.60 + ( 0.29 * Tin% ) + ( 0.92 * Antimony% )

Example: Lyman #2 (consists of 5% tin and 5% antimony) = 8.6 + (0.29 * 5) + (0.92 * 5) = 14.65 BHN

How do you weigh 4.8 oz of tin? Other than getting tin from RotoMetals and cutting it I see no way to measure this. I have a postal scale from the early 70's that will weigh up to five pounds but I've shied away from pure tin due to the cost. If I had as much tin as Linotype I'd be rich.

[Cranium]

I get bars of tin from RotoMetals in 1-4 lb bars.
http://www.rotometals.com/v/vspfiles/photos/TinIngotForm-1.jpg
I then use my Lee 4-cavity ingot mold
http://media.midwayusa.com/productimages/medium/361/361222.jpg
along with my Maxi-matic hotplate
http://ecx.images-amazon.com/images/I/31yHovBp7VL._SL500_AA280_.jpg
along with my digital 25 lb capacity scale (sorry, no pic for that).

I hold an end of the tin bar at the bottom of the mold on the hotplate set to high. Since the melting point of Tin is 450 °F, the hotplate is adequate to melt the Tin. I hold the other end with gloves (one glove holding another wrapped around the bar). As the bar gets smaller, you'll have to hold the bar with channel locks or something. But since the weight is less, this isn't too much of an issue.

To determine how much I'm melting, I use two processes but prefer the first:

Weigh the bar as the start of the melt and then periodically weigh as I melt to know how much has melted off in the mold
Weigh the mold as it fills to determine how much weight is in each cavity.

I can get accurate little ingots within about .3 oz in just a short period of time that will be good for my future alloys. I usually only do a few at a time though so I can more easily adjust if my alloy recipe changes.

[milprileb]

My head hurts. Will you scientists pls pontificate on another thread? I just want to
know how much tin (and where I can get tin) to add to my WW and Lead alloy so it will fill molds nicely.

Can we ratchet this down to mere mortal level and help me out. I don't got a science degree, only a Infantry degree.

[ColColt]

Very good, Cranium. Excellent synopsis and one for my future use. By Jove, I think you've got it.


My head hurts. Will you scientists pls pontificate on another thread? I just want to
know how much tin (and where I can get tin) to add to my WW and Lead alloy so it will fill molds nicely.

Can we ratchet this down to mere mortal level and help me out. I don't got a science degree, only a Infantry degree.

OK, Private here it is., Unless I'm wrong you add about 3.2 oz of tin to 10 pounds of ww's and you're good to go. Someone correct me if I'm off on this.

[milprileb]

Fire for effect !

Thanks for the fire support.

[Cranium]

Thanks ColColt.

milprileb, go to this thread and download the Lead Alloy Calculator spreadsheet. It will help you determine these alloys for the most common sources of lead. This is what I use for my alloys as a baseline.

http://castboolits.gunloads.com/showthread.php?t=105952&highlight=lead+alloy+calculator+spreadsheet

If you have any questions about using it, feel free to ask. :)

[milprileb]

Oh yeah... that is gonna consume me for awhile. You scientists go back to your mad
experiments and unknown tongue discussions... I won't interrupt for a good while.

[Cranium]

ROFL....now that is funny. :D

[prs]

Oh yeah... that is gonna consume me for awhile. You scientists go back to your mad
experiments and unknown tongue discussions... I won't interrupt for a good while.

I'll take my think'n cap off. If your WW alloy is of clip on deisgn, then you prolly have a product that will cast well as is. If not to your liking, remelt the boolts and add 1% tin to pot and try again. Repeat, if necessary (it should not be). Trial and error is science eonugh for many purposes.

You can get tin at scrap yards, or buy lead free solder $, or RotoMetals has several selections that are neat and easy.



prs

[milprileb]

PRS:

The clip on WW melted, fluxed and poured do just fine in RN 9mm and 45 RN acp molds. Then I added the 1.5 # of lead as pure WW did lead up 9mm barrel. Ran a batch of this new alloy and shot the 45 acp SWC bullets using this allow for first time: very accurate at 25 yds but bullets do not drop from mold crisply filled out so I was thinking my problem is lack of tin. These bullets gave no leading whatsoever. Thats fine but in 45acp, I was getting no leading regardless of alloy, its in 9mm that my drama with leading was showing up.

Odd though, this WW and 1.5# of lead alloy in 9mm RN mold drops perfect bullets but not in 45acp SWC mold (HG 68 Lee Clone)

Some Voo Doo is happening here with the 45ACP SWC mold. Not sure what, bullets fire just fine but will chase more tin and see if that makes better looking bullets. If not: I can live with results so far.

Still got to test the 9mm loads using this new WW & lead alloy and sized .357 this time (was doing .356 before). I am hopeful new allow and sizing will end leading and bring optimum accuracy in my pistol, a 1911 9mm Taurus. (on my High Power, the old load using pure WW metal and .356 was accurate and zero leading so clearly, I got to tailor loads in 9mm to pistols used ).

Lots of great advice and help offered here and I thank you and others for assistance. I may need tin and may not. May need it only in 45acp SWC mold use and not in RN mold. Seems I don't need it for my 9mm RN mold.

Chasing variables at the moment. At least I am not chasing molecules but I might end up like those mad scientists yesterday on this forum !

[williamwaco]

---------------------------------------------------------------------------------


In a lead solution, antmony and tin will form what is called an intermetallic bond called Sb/Sn, and is roughly 50/50. This intermetallic is responsible for making boolit metal tough as well as hard. Too much antimony and it will be very brittle, any significant antimony without at least a touch of tin has a greater tendency to "lead" the bore. Too much tin, i.e. more than the amount of antimony present, causes it's own problems, but that's another story.

Gear

---------------------------------------------------------------------------------

A blast from the past!

Many years ago, around 1960, wheel weights were much harder than they are now. I don't really know how hard because in those days only Lyman had a Brinell hardness tester.

We tested the hardness of a new batch if wheel weights by melting the weights, cleaning out the gunk and clips, fluxing until nothing more floated to the top.

Then we would cast a few bullets and set them aside to cool. after they reached room ( or garage ) temperature, we would lay them on the garage floor and whack them with a hammer. If they flattened, we cast up the rest of the pot ( or poured ingots ) If they shattered, we added an equal amounts of scrap lead and a little tin. The tin came from bar solder.

[Tom Herman]

How do you weigh 4.8 oz of tin?

ColColt,

I can see where things might wind up exasperating.... I managed to get in on the Grainger Tin solder deal a few years ago, and put away close to 50 rolls of essentially pure Tin solder for $5 a roll...
Measuring the weight of it is fairly easy: You can unroll the entire roll and divide the length in feet by 16 to get feet per ounces, or divide 16 by the length to get ounces per foot...
I have to double check my figures, but something like exactly ten feet hit my magic number for 50/50 scrap lead plus wheel weights to get me to 2% Tin.
Cutting ingot material to be dead nuts on can be a pain.
I did have a small stock of 50/50 solder bars that my last employer threw out (!?!), and I divided the bar into 16th's with a magic marker, and simply inserted it into the pot and melted off until I got the right amount. Sure, it wasn't dead nuts, but close enough.
I did pick up an electronic scale that goes to tenths of an ounce. Works well, too...
Good Luck!

Happy Shootin', -Tom

[geargnasher]

My head hurts. Will you scientists pls pontificate on another thread? I just want to
know how much tin (and where I can get tin) to add to my WW and Lead alloy so it will fill molds nicely.

Can we ratchet this down to mere mortal level and help me out. I don't got a science degree, only a Infantry degree.



Between 1/2% minimum and 2% maximum total is all you need for any Pb/Sb/Sn alloy containing at least 2% Sb. Simple enough? Wheel weights have almost enough to work fine by themselves if you are a proficient caster, if you think you need some tin for better fillout often the full effect of tin will be realized by only adding one percent to the mix. If that doesn't do it, you have a mould temperature or an alloy contamination issue.

Keep your tin-bearing boolit metals cooler than 750 degrees or you will have problems regardless because the heat destroys the oxidation barrier/surface tension reducing effect of the tin.

Gear

[geargnasher]

While you may be technically correct in the statement that the additions of Sb & Sn in different proportions do not result in a BHN that can be represented by a linear equation, it is still a very good formula to use and is quite adequate for the limited range of hardness used for casting bullets.

A good reference for this type of data that I've learned much from was written, in part, by Glen Fryxell who has a PhD in Chemistry and whose professional interests were in part nanostructured materials and molecular self-assembly. He lays out the foundation
http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m

The equation is also referenced on Rotometals.com (http://www.rotometals.com/Bullet-Casting-Alloys-s/5.htm) and doing a Goggle search will reveal this equation's usage elsewhere as well.

So, while not exact science, it is a good thumb rule. And if you have an alloy tester that is exact enough and repeatable enough to ±.1 BHN (consumer testers are not), you can tweak your alloy a little to get the exact BHN you desire.

For reference, the reason I state that consumer testers are not accurate enough for repeatable, accurate results is based on the study found here: Testing The Consistency Of The Commonly Available
Cast Bullet BHN Test Equipment (http://www.lasc.us/Shay-BHN-Tester-Experiment.htm)

You didn't put that in APA or MLA format, you're slipping! :kidding:

My point was that, if you use alloys outside of the spectrum listed, the formula is useless, as well as having inaccuracies within the useful scale. I bring this up because a new caster, or a lurker searching this thread for the meaning of tin, might take that as gospel and wonder why his bh numbers are off with his mix of 8% Sb and 2%Sn, or why he can't get his Pb/Sn binary any harder than 11 even though he's added enough tin to make an 8:1 ratio. What if I want an alloy to contain equal parts Sb and Sn, but wanted it to be about 7.5 bhn for .45 Colt? Out of luck with that formula. Have you tried it on linotype? Works great, but take away half the tin, what do you have? Sure, it's a decent guideline for regular boolit metals if you know the limitations of the formula, and are familiar with the general properties of boolit metals, but you have to consider the person who doesn't, and who's reading this, and who might print that out and nail it to the wall over his casting pot, and might get confused as heck.

Another point of fact to consider: You may criticize an ordinary mortal for not having a "real" bhn tester, but also consider that (with antimonial alloys) there will be far wider variations in bhn from one caster to another due to the temperature at which the boolit leaves the mould, or the altitude or weather, than there will be between even hobby-level bhn testers of the same brand. Next batch of boolits you cast, check the hardness of the tenth, hundredth, and 300th one, and tell me what you get.

Gear

[Cranium]

To quantify adding Tin....

Using wheel weights and adding enough tin to get it to 2% will require about 1/4 lb and cost about $4.75 / 1000 rounds when casting 9mm, 120 gr bullets. For 45 ACP 230gr, this would be about twice that.

These figures are based on buying pure Tin from Rotometals. Tin is expensive by the pound but cheap per bullet to get the alloy to 2%.

[prs]

PRS:

The clip on WW melted, fluxed and poured do just fine in RN 9mm and 45 RN acp molds. Then I added the 1.5 # of lead as pure WW did lead up 9mm barrel. Ran a batch of this new alloy and shot the 45 acp SWC bullets using this allow for first time: very accurate at 25 yds but bullets do not drop from mold crisply filled out so I was thinking my problem is lack of tin. These bullets gave no leading whatsoever. Thats fine but in 45acp, I was getting no leading regardless of alloy, its in 9mm that my drama with leading was showing up.

Odd though, this WW and 1.5# of lead alloy in 9mm RN mold drops perfect bullets but not in 45acp SWC mold (HG 68 Lee Clone)



You already have the solution. Use the original ww alloy in the .45 auto and the blend in the 9mm. No harm, other than to your pocket book, in adding 1% tin to the alloy to see if the 45s drop pretty. The additional hardening will be very minor and the added toughness may be significant. I should not take much time to drop nicely formed/filled pill and adding more is expensive. It is a S"i"n to waste tin ;-)

But since you have combos that are working, you are good to go. For sizing lead boolits, the less the better. If it chambers, the gun will size them. Lube-sizing; use the largest die that yields boolits that chamber reliably. No complications.

prs

[Cranium]

My point was that, if you use alloys outside of the spectrum listed, the formula is useless, as well as having inaccuracies within the useful scale. I bring this up because a new caster, or a lurker searching this thread for the meaning of tin, might take that as gospel and wonder why his bh numbers are off with his mix of 8% Sb and 2%Sn, or why he can't get his Pb/Sn binary any harder than 11 even though he's added enough tin to make an 8:1 ratio. What if I want an alloy to contain equal parts Sb and Sn, but wanted it to be about 7.5 bhn for .45 Colt? Out of luck with that formula. Have you tried it on linotype? Works great, but take away half the tin, what do you have? Sure, it's a decent guideline for regular boolit metals if you know the limitations of the formula, and are familiar with the general properties of boolit metals, but you have to consider the person who doesn't, and who's reading this, and who might print that out and nail it to the wall over his casting pot, and might get confused as heck.

Another point of fact to consider: You may criticize an ordinary mortal for not having a "real" bhn tester, but also consider that (with antimonial alloys) there will be far wider variations in bhn from one caster to another due to the temperature at which the boolit leaves the mould, or the altitude or weather, than there will be between even hobby-level bhn testers of the same brand. Next batch of boolits you cast, check the hardness of the tenth, hundredth, and 300th one, and tell me what you get.

Gear

Yep....I agree with your specific points. But I hope you aren't implying that people should not use the equation because you can prove it can be not applicable in every application.

Webster defines rule of thumb as: a general principle regarded as roughly correct but not intended to be scientifically accurate.

I think the equation should not be discounted because a person may not comprehend the application of a thumb rule. It is good; however, to remind people of the definition. :)

As far as hardness testers go, I'm not discounting them at all. I own a lee. I think everyone casting should have at least one. But people should also realize these testers are also guidelines (like thumb rules) and are not true scientific results.

[geargnasher]

Thank you for "toning it down". I wasn't attacking you, or implying that you were wrong, and I wasn't implying that people shouldn't use the equation, either. I don't know where you read that implication into my posts. I was merely tempering your information with a small dose of "caveat", which I thought I explained pretty well with a few examples so folks could see both the validity and the limitations of the formula you posted. It's not that people need to be reminded of the definition of "rule of thumb", it's that people need to be reminded that the FORMULA ITSELF ranges from very accurate to off the map, and I felt that the useful and accurate part needed some definition for the presentation of the formula to be complete.

Gear

[Cranium]

Thank you for "toning it down".

Your welcome and I apologize. It is sometimes easy to misinterpret the tone of text. And it's also easy to get caught up in a debate. I'm not looking to attack anyone but do enjoy a friendly debate. :) I realized afterwards that I was starting to turn it into something it did not need to be.

So, if people are to be reminded that the formula can be 'off the map', what should they use to base alloys on? And at what point does it go off the map? Is there a thumb rule to use for the thumb rule?

Without some clearer definition, I feel people will get more confused when trying to make a decision on developing an alloy and thus be unable to do so. This is why I just use the formula and test the results to see if there are any discrepancies that need to be addressed. I haven't run into any issues so far but I'm only casting for 9mm at this point.