Zinc bullets, why harder on bore than copper? [Archive]

jabilli

01-26-2013, 10:37 PM

So I'm a bit confused-

I understand that a well designed bullet will deform upon having the heat and pressure from the expanding gas of the cartridges charge...This deforming will better seal the bullet to the bore and will allow less blowby- minimizing gas cutting. The bullet, or gas check, has to be soft enough to allow for this.

I also understand bullets with a full metal jacket do not expand in this manner, but rather are made to more extreme (tight) tolerances.

I was looking into using zinc for cast .223 as lead simply dissipates at any kind of speed, even with a gas check, and full metal jackets require swaging equipment.

My point of confusion is, I'm told zinc will wear a barrel very quickly... I look at the brinell hardness of zinc and it is in the realm of 400... I look at the hardness of copper and it is around 800... I don't disbelieve the experienced, I'm just confused as to why?

500MAG

01-26-2013, 10:50 PM

If you can keep your mold hot enough to get good boolits, you then need to think about load data for the odd weights. Where would you get load data. Also, I don't think the zinc would grip the rifling to shoot straight.

longbow

01-26-2013, 10:54 PM

Not sure who told you that zinc would wear a barrel faster than copper but I am with you and think that is incorrect. There were boolits made that incorporated zinc "washers" essentially attached to the base of the boolit. These were called Pro-Tex:

http://castboolits.gunloads.com/showthread.php?94389-Zinc-driving-band

I see a few threads on them on various sites but no current availability. I don't think they did much of anything better than gas checks.

Corbin swaging offers a similar idea but for swaging copper discs onto boolit bases.

There are various grades of zinc/zinc alloy and some like Zamac/Zamak are used as bearing materials so these definitely would not wear steel any faster than copper. In fact I doubt a boolit made of zinc or any typical alloy would be a problem that way. the bigger issue is making zinc boolits. While some have tried it, I think it would be easier to machine zinc bullets the way the solid brass/bronze bullets are made than to cast it.

That's my take anyway.

Longbow

dakotashooter2

01-26-2013, 11:06 PM

I've often wondered if injection molding would be the best option for zinc. Seems it would produce a more consistent bullet with less voids.

I'll Make Mine

01-26-2013, 11:18 PM

I've often wondered if injection molding would be the best option for zinc. Seems it would produce a more consistent bullet with less voids.

They call it die casting when it's done with metal, but that's how many zinc items (drawer pulls, car door handles, lamp bases, and little bitty model cars) are made. Die casting should be able to produce large quantities of accurately dimensioned zinc boolits quickly, but what we do (casting in a mold) is exactly that, minus the sprue of dozens of parts all cast in a single shot.

Use an iron mold; zinc will bond to aluminum or brass. Cast hotter than you would with lead, and segregate your equipment so you never use lead with your zinc equipment or zinc with your lead stuff. Zinc bullets will work fine; they've been sold commercially, and in fact there are lead-free .22 LR rounds in current production that use zinc bullets.

You will probably want your zinc bullets a tiny bit smaller than lead for the same gun -- instead of one or two thousandths over groove, zinc should be at or a thousandth under groove diameter, generally. Zinc will not work well in applications that depend on the bullet upsetting to fill an oversize bore (say, a .32 or .38 Long Colt in a revolver originally made for the old style heeled bullet rounds, but loaded with inside lubed bullets, or a Webley Mk. IV made for hollow base) but in most conventional rounds and guns made today, correctly sized zinc bullets will work fine.

As for loading data, use minimum starting loads for jacketed bullets the same weight, and work up carefully. Zinc will have less barrel friction than jacket metal, so you should get lower pressure than the same weight jacketed bullet in spite of the longer bearing area due to the lower density of the zinc.

rsrocket1

01-27-2013, 01:01 AM

Wow, this might be the way of the future. If lead becomes illegal, at least we would be able to shoot with zinc bullets. But I suppose there would be some anti-gun environmentalist that will say zinc is toxic to condors too (especially if you feed it to them at 2750 fps).

runfiverun

01-27-2013, 03:08 AM

in the late 50's a company called jugular made and sold zinc bullets.
they are much lighter than lead so they require much higher velocity's to poke holes in things.
look back at all the trouble the duck hunters had/have with steel shot.
you have to speed steel shot up for it to penetrate,but it's light so it slows right down again.
so you make it bigger to carry more weight.
the bigger frontal area makes penetration harder.
so you speed it up again,,, oops you can't you run out of room for more powder.

fredj338

01-27-2013, 04:59 AM

Well zinc is certainyl softer than solid bronze or solid copper, so it's not that just getting the zinc to cast well is the bigger issue I would think. I know what zinc does to a lead alloy & makes getting good castings difficult. A smaller bullet like a 224 is making things even more so. If you can get it to mold, I see no harm coming to the barrel.

BAGTIC

01-27-2013, 12:53 PM

I don't know where you get your information but industry standards for Zamak #3, the most widely used alloy in North America, is BHN 82. Common recommendation for zinc alloy bullets is .001 over groove diameter. I take that to be a minimum of .001 inch as zinc is probably going to show very little if any expansion at acceptable pressures.

If one follows good loading practice and starts low and gradually increases load that will take care of different engraving forces due to bullet hardness. Once bullet is engraved there should not be any pressure differences. Zinc is so much softer than steel than wear due to friction should not be a problem. Army and Navy ordnance has used zinc projectiles for proof testing artillery for generations. I doubt they would risk damage to such valuable and expensive pieces if there was an increased risk.

It has been shown that jacketed rifle bullets with pure lead cores create higher pressures than ones with hardened lead cores.

BAGTIC

01-27-2013, 12:58 PM

Bigger frontal area of birdshot does not make penetration harder. As the shot becomes larger diameter it also becomes longer increasing sectional density. On 'soft' targets momentum density is the primary determinant of penetration.

runfiverun

01-27-2013, 03:58 PM

untill you make it light for it's frontal area.

Blammer

01-27-2013, 05:08 PM

so, is zinc oxide harmful?

popper

01-27-2013, 06:07 PM

I would think solid zinc would be like solid copper and increase wear, who knows how much. Jacketed just displaces the lead core. Pressure on lands of compressing solid metal is much greater. Obviously is does work, but the question was about wear.

Thompsoncustom

01-27-2013, 06:30 PM

Casting zinc is a lot easier than you might think. Here's is a pic of a zinc/alum bullet I cast and shined.
59649

I cast all my zinc in a plain Lee mold as I didn't want to mess up an steel ones. They do produce bullets that are a lot lighter tho, My lee 125gr mold throws 80gr zinc/alum bullets and my 102gr mold throws 60gr bullets. It's been about a year since I have cast any of these tho I just bought a mold the other day that I'm going to be playing with, already removed the lube groove but still have plenty of work to do.

500MAG

01-27-2013, 06:38 PM

Please stop it. This is enough. Everytime I turn around there is something new one of you guys is doing and I end up having to do it. I spend so much time and money on new casting equipment and processes I never get out to the range anymore.

45 2.1

01-27-2013, 06:58 PM

Please stop it. This is enough. Everytime I turn around there is something new one of you guys is doing and I end up having to do it.

Actually, most all of this is old technology. Most all these supposedly new ideas here have been done several times before... and written about.

Blammer

01-27-2013, 08:13 PM

59649

That's just really pretty.

I'll Make Mine

01-27-2013, 10:02 PM

I don't know where you get your information but industry standards for Zamak #3, the most widely used alloy in North America, is BHN 82.

Sure. But pure zinc is around BHN 30-32, as I recall -- similar hardness to some of the harder lead alloys we use.

BAGTIC

01-28-2013, 08:24 PM

A larger diameter sphere will always be heavier than a smaller one made of the same material.

BAGTIC

01-28-2013, 08:37 PM

Chicken Thief

01-28-2013, 08:54 PM

Soft iron and sintered iron driving bands for artillery projectiles were introduced at least as long ago as WW2 and are used by many counties today. At one time Norma produced steel jacketed hunting bullets and of course almost all military 7.62x39 mm ammo has steel jackets. If steel doesn't wear them out why should zinc?

The trick is copper plating to reduce friction.

And i'll bet you that a barrel wont survive 5000+ of them steel clad bullets with presition to spare.

But why not just swage the zink? Is there a need for lube?

Chicken Thief

01-28-2013, 09:19 PM

Zink Oxide ZnO has a hardness of 4.5 Moh~72 Rockwell :o

http://en.wikipedia.org/wiki/Zinc_oxide
http://www.cidraprecisionservices.com/mohs-conversion.html

Compare that to a rifle barrel of something around 40'ish Rockwell.

Then again copper oxide CuO has a Moh hardness of 3½-4.

http://www.galleries.com/Cuprite

Alu oxide Al2O3 is "pure" sapphire/ruby and a fine abrasive.

http://en.wikipedia.org/wiki/Aluminium_oxide

So lets just shoot and have fun.

Chicken Thief

01-28-2013, 09:25 PM

Just had a http://i295.photobucket.com/albums/mm153/Chickenthief/Blandet/Smilere/Brainfart.gif

Copper wears of and fouls a barrel, so does most other things.
How to clean Zink?

Thompsoncustom

01-29-2013, 07:03 AM

How to clean Zinc

sodium borate (borax) works as a flux for zinc.

jabilli

01-30-2013, 12:02 PM

Lots of great answers/info! Thanks guys :-)

The other day I got a small amount of zinc and a torch, heated up my mold (steel .223) and had about enough molten Zinc to fill one cavity and still have a sprue. I noticed immediately that Zinc doesn't seem to be as fluid as lead (I'm guessing this can be remedied by hotter temperatures?) It was reluctant to move...then suddenly and very quickly moved when it finally did. >< After pouring, it solidified faster than I would have liked: I found the sprue wouldn't break... (at least with the amount of force I was willing to place on it.) I chose to partly disassemble the mold and Dremel the bullet out. It formed pretty well, especially considering it was the first cast (usually the first few of my lead boolits turn out kinda, "Meh.") and how short the amount of time it was in the mold before solidifying.

It seems a few places talk about shooting Zinc/Aluminum alloys...My question...Why Aluminum?? What does it do/give you?

I'll share what I have found out about about Zinc/Aluminum alloys It seems that Zamak is the trademarked name for a family of alloys... Zamak 3 is the alloy of theirs that is a base for all of their other alloys. Zamak 3 is 96% Zinc, 4% Aluminum. The alloys are known for being the material many components (Including slides, receivers, and bolts) are made of in Hi-Point's firearms.

From what I read, to mix in Aluminum in molten Zinc, people are simply stirring it in the Zinc and it dissolves (Amazing really, considering the melting temp of Aluminum is something like 1200 and the zinc is much lower, something like 800ish I think)...I read this to be done with solid objects like rods...Anyone know if other forms of Aluminum can be mixed in?? (Powder/molten) I read somewhere it can be fluxed with Aspirin (salicylic acid)...I'd double check on that, sounds potentially harmful.

I do know that casting with pure Aluminum causes shrinkage...Objects cast come out something like 2% smaller after they cool. I wonder if this has any effect on Zinc/Aluminum bullets... Anyone know ?

@ Thompsoncustom- Wow look at that, looks like a piece of jewelry. :-p Have you gathered info (Loads/performance data/ Accuracy/notes about wear/ect.) about those bullets by chance? How do you make them? (As you can read above, I ran into some trouble getting the sprue to break.) Related to my shrinkage question above- What size do they drop out at?

Thompsoncustom

01-30-2013, 03:41 PM

LOL you got to be quick and hit that thing as soon as you pour the bullet pretty much. I've cast oh maybe 100 but never got around to testing them for accuracy. I used Quickload to help in developing loads for the light bullets. I don't think they wear any more than copper bullets but they do take a little more force to size than lead ones.

I noticed immediately that Zinc doesn't seem to be as fluid as lead
When I start casting pure zinc bullets I noticed the same thing and that's the reason I add aluminum to mine seems to be like adding tin to lead bullets. A pop or beer can works well as they are really thin and dissolve easy into the zinc not sure on the temp it takes but around 800 sounds right maybe lower. Ya it's weird to think about but your not melting the alum your dissolving it like salt in water.

I do know that casting with pure Aluminum causes shrinkage...Objects cast come out something like 2% smaller after they cool. I wonder if this has any effect on Zinc/Aluminum bullets... Anyone know ?

I don't really remember but I don't think they cast smaller because I sized them to .3565 and it was shaving them.

My latest project with zinc is going to be trying to make a hard nosed bullet with the front half being zinc/alum/and maybe some copper and the back half being lead. Tho the cheap lee mold I got for the project needs a lot of work I already removed the crimp groove but need to make the nose longer and shave the top 1/4 of the mold so I have no idea if this is going to fail from the start or not but lee molds are cheap so I figured why not.

jabilli

01-30-2013, 04:07 PM

Very cool, thanks for the info.

Interesting idea- Best of luck, stay safe. I spent a minute or two trying to think of a way to make a bullet with a lead rear and a Zinc front, and have each one be almost exactly the same...I'm curious if molten Lead would adhere to Zinc...If so, you could cast out a bunch of noses (cut to same size/shape via a sprue) , then take the noses and place them in a mold point-down where you could cast the rear of each bullet on top of each nose. Sounds unlikely to work.

Probably a more likely thing to work would be to cut a thin lead disc, then sandwich it between the base of a bullet and an attached gas check.... Wonder if that would work. OR...if having a lead base isn't an issue, a gas check made O-lead?

Thompsoncustom

01-30-2013, 09:07 PM

those sound like some great ways to do it but I was thinking something much simpler. I am planing on cutting a dipper to only hold the amount of zinc I want per bullet and then filling the rest with lead but I'm not sure how they will adhere as the zinc will have to start to set up a little but should be hot enough to keep the lead molten for a bit. Because if you mix the two molten the heavier one will sink. Doesn't have to look pretty just has to work.

williamwaco

01-30-2013, 09:54 PM

MikeS

01-31-2013, 02:54 AM

Why would you want to remove crimp grooves, or lube grooves? I would think that even if you're not going to use lube (it's not really needed with zinc boolits) that you would be better off leaving them. First off it would lower the amount of zinc in contact with the bore and so would lower the friction of the boolit going down the bore, and also, just like the solid copper (or is it brass?) bullets have grooves in them, that leaving the grooves in a zinc boolit would give it the same advantages as the copper bullets. I forget all the reasons they put the grooves in the copper boolits, but I'm sure the zinc boolits would have the same reasons for having them. And a crimping groove? no reason to remove it, unless you feel you will NEVER crimp the boolit in place. Even jacketed bullets that are designed for cartridges where the bullets would be crimped in place have crimping grooves, only they don't call them that, they call them a cannalure (sp?).

jabilli

02-02-2013, 12:02 AM

Williamwako-
Cool find- thanks!

geargnasher

02-02-2013, 12:25 AM

BAGTIC

02-02-2013, 01:50 AM

At least four countries are already using steel bullet. France is one and Nammo which supplies ammunition to Sweden, Norway, and Finlands has developed steel bullets which have been accepted by the military.

Here is a link to a 1951 paper related to the development of soft iron driving bands for the high performance 3/70 naval AA gun. It shows that the hardness and friction of the iron bands is no higher than for copper. If 1951 metallurgists could manage it I think modern ones could do at least as well. Now none of this will help those who want to make their own at home but it shows that just because something has never been done before or because we have never heard of it is not cause to say "It can't be done". www.dtic.mil/dtic/tr/fulltext/u2/499469.pdf

jabilli

02-03-2013, 04:15 AM

Interesting read!
First thing that came to mind: Who were the poor fellas that had to go find and retrieve the projectiles? lol "The average ranges wore 14098 yards and 14036 yards, respectively."

I've found something in particular this article mentions to be thought provoking...Before I jump on it excitedly only to feel like an idiot later, I'll spend a bit of time reading into it first. :-p

The document seems to me to have been a request for more testing (send money please.)...I wonder how it was received?

IMO, If I were charged with the task of arming a naval ship with an AA gun- given the choice between wearing the barrel to be more accurate, or choosing projectile materials that conserve the bore, no doubt, give me the barrel wrecker. A nicely treated bore won't be of any use at the bottom of the sea.

BAGTIC

02-03-2013, 12:16 PM

1) Zinc bullets don't need lubricating.
2) Grooves in the bullet degrade the ballistic coefficient.
3) Grooves result in a longer bullet which reduces case capacity.

BAGTIC

02-03-2013, 01:00 PM

This particular gun was notably unsuccessful due to problems with the mounting. After 12 years the Navy gave up partly because by that time the age of the SAM was fast approaching.

What I found interesting was the observation about where the greatest bullet (driving band) erosion occured. It was not atop the lands or in the bottom of the grooves. It was against the leading edge side. One the projectile had been engraved there would be little wear or friction except on the back side of the rifling where most of the stress occured. This points out the nature of rifling or any other screw as being an inclined plane, like a ramp, and most of the wear occurs on the load bearing side.

BTW the barrel was chrome plated and water cooled. Normals barrel life was 2,050 rounds when firing the ultimately adopted load (45,000 psi ) of 11.2 pounds of powder propelling a 15 pound projectile at 3,400 fps. ROF for a twin mount was 90-100 rpm. This compared with the older twin 3/50 3 inch gun which fired a 13 pound projectile ahead of 4 pounds of powder (34,000 psi)at 2,700 fps at 45-50 rpm with the same barrel life of 2,050 rounds. It seems that despite much higher performane barrel life did not suffer from the iron bands.

jabilli

02-06-2013, 03:00 AM

Zamak "cores" when it shrinks, as do most zinc alloys and pure zinc. Someone here built a vibrating mould rest with an electric razor to assist fillout and reduce coring. Traditional sprue plates are insufficient to cut zinc without tearing them up in short order, special moulds with something like a sprue-hole-sized gas check shank and integrated sprue well would work, the sprues can be cut off after casting but would make cherry-cut moulds really difficult to make considering the weak point in the cherry.

As far as bore wear goes, anybody consider what is in gilding metal alloy?

Gear

I'm thinking I will try to use higher operating temperatures which allow me a little bit more time to cut the sprue while semi-molten. Afterward I'd just buff out any lines. If not- it seems cutting might be the way to go- Someone else in the forums claims this is his standard practice- I'd like to throw out his name but I forget who it is and searching for it just now did not bring up his post. :-(

1) Zinc bullets don't need lubricating.
2) Grooves in the bullet degrade the ballistic coefficient.
3) Grooves result in a longer bullet which reduces case capacity.

Personally I'd (at least for now) rather not alter my mold, given a choice.
I'm quite confused as to the third statement: "Grooves result in a longer bullet"... hrm? I do understand that under pressure from being fired a bullet with grooves lose a bit of length due to being squished from the pressure/obturation (...Someone verify this please?) but I don't see how having grooves will make a bullet longer (thus causing higher pressures when given a static OAL)? Am I missing/misunderstanding something?

I have read that lubing cast zinc boolits isn't neccesary from another thread or two, one even citing an old magazine article making this claim-
Not for the purpose of "HEY I DON'T BELIEVE YOU/THEM" but, are we sure this is so? Thinking out loud for anyone that's wondered this:

Questioning whether or not lubing is necessary, we might first ask- What does lube do?
1. Help fill in gaps where air may try to pass through (even .001 can let a relatively large amount of gas through under pressure) thus minimizing gas cutting, thus reducing bullet deformation and leading.
2. Helps reduce leading via lubricating the contact point between the bullet and the bore.

Considering this, why is lube not needed for Zinc?

This got me wondering, "Hey...Why don't we lube jacketed ammo?"
A quick google brought me here: http://www.leverguns.com/articles/taylor/bullet_lubes.htm Interesting to have a gander at.

IF this is so, I'd imagine the main reason for why it is not commonplace for jacketed ammo to be lubed is that it might be much harder/more expensive to make swaging equipment that makes jacketed projectiles with lube grooves.

captaint

02-06-2013, 08:01 AM

All this discussion is great, BUT - why doesn't somebody just go pour up some Zinkers, load & shoot them and tell us all how they worked ?? After all, that's what we want to know anyhow !!
So, jabilli, go make some and get back to us, please !! Mike

I'll Make Mine

02-06-2013, 08:14 AM

I'm quite confused as to the third statement: "Grooves result in a longer bullet"... hrm?

I think that was meant as something along these lines: "A lube groove boolit will be longer than the same weight without grooves, hence potentially reducing case capacity if it has to be deep-seated to avoid interference with the rifling when the round is chambered."

jabilli

02-07-2013, 11:22 AM

jabilli

02-07-2013, 11:27 AM

Oh hahah Lightbulb :-) Thanks

jabilli

02-09-2013, 09:33 AM

Alright. Progress :-)

So it seems Zinc is a lot less readily available than I had thought. It IS used just about everywhere, but most commonly in electroplating. I was under the impression that I could go to the hardware store and pick up some large washers made -o- Zinc. Yeah- I wish. I do believe I might be able to procure a larger quantity of Zinc at a tire shop, but for now, I had a smaller amount readily available at home...(Don't ask, I won't tell.)

I got my turkey fryer up and going (I had spilled some lead down in the cast iron pipe of the burner, blocking it, so I had to go in and melt it out with a torch...What a PITA...) and got a nice amount of some shiny liquid Zinc, Fluxed with a paraffin candle (The small kind that comes in that little Aluminum case) and Borax. As I'm typing this I'm letting the Zinc cool into a little Zinc-patty, so I can weigh it...So I can get an accurate figure for how much Aluminum to mix in. (Zamak uses 4%...) Since my last posting, I've read a host of info on the subject- Bookmarked a few, will include in my post after I'm done. (will make a separate post, pictures, info, recorded stats, what have you.)

SOO my largest hindrance (at least I hope) has been tackled (obtaining the Zinc itself, then melting it without using my equipment that I use for casting lead...I didn't wanna use my bottom pour melting pot....had to fix turkey cooker) Now it's mixing in Al, casting boolits, loading them, then spending some quality time in front of my chrony with my poodleshooter.

Additional tidbit- I measured that boolit that I made last week and cut away from its sprue... .223. I was considering the fact that if the Zinc boolits do not obturate/"grab the bore" paper patching (with PTFE tape :-P ) may be the best option. Anyhow....Thought that might be something people might be interested to know.

Thompsoncustom

02-09-2013, 11:09 AM

oldpara

02-09-2013, 11:24 AM

jabilli

02-09-2013, 11:55 AM

Boy I tell ya, nothing is quite like having everything you need necessary to get the job done, ready and on hand. This is not the condition of my tools/materials right now. (Ran out of propane) >< :x LOL

So I brought my turkey cooker up to temp and added in some Aluminum. Had it not been for me reading somewhere that it takes a minute or so for the Aluminum to dissolve into the melt, I would have given up trying a little too soon (and thinking what I had read was bunk. Haha). Give it a minute.
Tips:
1.Surface area is your friend- Aluminum foil really melts quickly.
2. Aluminum cans really stink, badly, when melted. I think this is due to the paint. Be sure to slag out dross afterward as this paint is an impurity.
3. 16 oz Energy drink cans weigh 235 grains with their top popper thingy (Is it called a key ring?) removed. (I read somewhere the composition of the tops were slightly different...added nickel for hardness or something) I figured a few grains of each can would be drossed out.

I measured my Zinc patty (when it dried) to be 2.5 Lbs, So I wanted at least 700 grains, maybe a titch more ( I read somewhere having less than 4% is a severe detriment to whatever properties the Aluminium gives, and anything over I think it was 6% has diminishing returns.) The melt seemed to have a more shiny lustre.

I'll admit- While I DO have a nice $20 hand pouring ladle (this model= http://www.midwayusa.com/product/286579/lyman-lead-dipper) I am terrible with hand casting. When I say terrible I mean it. I learned quickly why some people use rubber mallets to whack the sprue plate, and other people use their glove... Hand casters already have a mold in one hand, and a dipper in the other... While possible to set down the ladle and pick up the mallet, life seems easier using the glove. Especially since I was trying to break the sprue plate while the alloy was still hot. As I was doing all of this- my propane tank had been slowly dying. I did what I could, but while working with this material at just barely above melting temperature, I found I had close to no time between pouring and breaking the sprue... I had to heat the mold as well as I could before pouring. The alloy is , unlike lead, a lot more CRUMBLY. When I broke the sprue, rather than staying intact, the almost-molten alloy would crumble off...That is, unless I gave it a second or two more to cool. Since the mold was so cool, I had a real picnic trying to get most of these boolits to drop out of the sprue. A couple times I couldn't even pick them out with my stirring spoon! I'm hoping when I get another tank-o-propane, I'll be able to have much higher operating temps, then, the boolits will plop out nice and happy like.

Weight? Without obvious deformations, 37.3 grains. I say "Without OBVIOUS deformations" because it seems to me that, as others have admonished, there is evidence of air bubbles. I say this because if you look at where the sprue cut, there are tiny tiny craters, where air bubbles were cut in half. I'm hoping that with higher operating temperatures, the alloy will have more time to settle (At this temp I literally would have about 1-3 seconds before it would "flash"...or harden. An odd tip- I found that if the alloy was resisting going through the sprue hole, tapping it with the pouring ladle actually pushed, or somehow encouraged the alloy to go into the cavity...It seems the surface area is gnarly strong, so my guess is some encouragement breaks the tension, and allows the alloy to flow. Again...While saying this I annoy even myself, I'm guessing with higher operating temperatures, this will be remedied.

Sigh.... 8. That's how many I got out before the turkey cooker wouldn't keep the alloy liquid any longer. 8 stinking boolits.... I'm quite frustrated..... (especially since I've no money, and a tank costs $20...When I say no money, I mean, I-haven't-had-a-job-broke.) I'm considering going and setting up a campfire in the back yard to continue.

Measured these- Micrometer was bouncing between .223 and .224...Perhaps due to me not being a professional with using the thing...but my guess is that it's somewhere in the ballpark of higher .223x (like .2237") and that it will shrink slightly, to give the solid .223 that I read on the boolit I cast last week. (The one from last week was stictly Zinc though...Still...)

jabilli

02-09-2013, 12:50 PM

PICTURE TIME!

60774
Note the rougher texture. One or two have a rounded base, not by design, but as caster error. One or two of the bases may seem to have some rounding but to a much lesser degree- This is due to me trying to pry the dang things out of the mold that was too cold.

60775
A picture of the air bubble craters.

60776
Another picture of the craters on a different boolit. I've attached two pictures of this because it's hard to see, even with this (IMO) nice camera definition.

60777
I'll be honest, part of me thought the fact that Aluminum dissolved in molten Zinc was total bunk. I took this picture for anyone who feels the same. (This rod was cut flush)

60778
This material is hard. I've circled it because it may be hard to see: The two tiny gashes/lines you see are marks from me squeezing the boolit as hard as I could by hand with a pair of needle-nosed pliers.

60779
For comparison: A wheel-weight boolit. ( Yes, I know the lighting in each picture is different. This is because in similar conditions as the WW boolit, I couldn't get the marks to show.) According to the Funmak (owners of Zamak copyright), the alloys hardness is 100 as cast (98 aged).

For whatever reason if anyone wants me to email them the pictures, please PM and I'd be happy to.

fcvan

02-09-2013, 01:18 PM

After reading a bunch of the comments about casting and sprue plates I was reminded of old plier type molds I had seen. There was no sprue plate, just the fill hole at the top. A round ball was cast and the sprue was cut later with a knife or nippers.

So, how about a zinc/alum. alloy boolit mold designed as a nose pour flat point. Worry about cutting the sprue after it has cooled. You don't really have to worry about a weak point in the cherry or cutting the sprue before it got too hard. As far as lube goes, I'd look at liquid alox or powder coating the boolit. If you really had to have shiny boolits they could be left plain or just powder coat the body of the boolit and leave a shiny tip.

jabilli

02-09-2013, 01:29 PM

I'm very interested in how zinc bullets work for you in a rifle as these things are going to be super fast with the reduced weight I wonder if they will keep there accuracy. Short penetration on a bullet of this kind of hardness and speed should be very good say 1/2 steel? Looking forward to your project.

Glad to hear the info is of interest. :-) I'll be honest: As I write about casting with Zamak and as I test and write about shooting with the stuff, I'll try to keep it as accurate and bias-free as I can. If the stuff shoots as well as a petrified turd, I'll tell people it shoots like a turd. I'd rather not lie to look good (or save face, or, for whatever reason.), then have someone try it later to be disappointed. Besides, other people have done this before, it's just I find it hard to find solid info on the matter.

Already I have a few concerns- Weight. Not a surprise, but it's turned out a bit lighter than I was originally hoping. A gas check adds 1 grain (Easy to scoff at, but when 1 grain is 2.5% overall weight, it should help.) A 3-4" length strip of Teflon tape (cheapo grade) weighs .5 grain. I'm hoping casting with hotter temps will cut back on air bubbles-maybe giving some weight. I'm reasonably certain there could be other methods of beefing it up, and maybe the mix of the alloy could be tweaked this way or that...Just..for now I wanna keep it close to what the book says Zamak 2 is.

Hardness- If the bullets are too hard to engage the bore, then the caster/shooter may as well be using any hard alloy. The nice thing about Zamak over the other options, though, would be ease of production. :-)

Anyhow, I'll be sure to keep ya posted.

fredj338

02-09-2013, 01:36 PM

Soft iron and sintered iron driving bands for artillery projectiles were introduced at least as long ago as WW2 and are used by many counties today. At one time Norma produced steel jacketed hunting bullets and of course almost all military 7.62x39 mm ammo has steel jackets. If steel doesn't wear them out why should zinc?
Well true, but govt never worried about the gun/bbl longevity. Steel jackets or driving bands certainly cause greater bbl wear, but nevr an issu w/ govt during war.

I'll Make Mine

02-09-2013, 04:20 PM

I'm not sure why all the effort trying to make Zamak to cast bullets, when pure zinc is easier and the resulting bullet softer (= less likely to give problems related to too-hard bullets, like excessive pressure at engraving and poor terminal ballistics for a lightweight, non-deforming bullet). Zamak is BHN 100 as cast, it says above; pure zinc is BHN 30 (which is comparable to the harder lead alloys we use, like linotype -- annealed pure copper, by comparison, is BHN 35).

Most of the objections to use of pure zinc in other applications (creep, for instance) don't apply to bullets, but objections of excessive hardness are much greater for a material that's hard all the way through (like Zamac) compared to a mild steel jacket over a lead core or outer core -- in the latter case, it's the soft inner material that determines the deformation energy on engraving, so that a steel jacketed lead or lead/steel bullet will require less effort to engrave than a solid copper or pure zinc one, never mind Zamak.

The aluminum in Zamak may also affect the lubricity of zinc; pure zinc slides easily on steel, but I don't expect Zamak to act the same way. The sliding friction is likely much higher than pure zinc, likely comparable to steel on steel (as with a steel jacket), but exacerbated by the higher normal pressure (due to the much higher body hardness) as compared to a steel jacket over lead.

Bottom line, I'd start very light when loading Zamak bullets, or better yet try driving one through the bore with a rod (largest size steel that will fit, protected from bore contact, since it's probably going to flex) to compare effort to that needed for a hard cast boolit or pulled steel jacket pill.

jabilli

02-09-2013, 06:10 PM

I chose to make Zamak rather than just plain Zinc for the purpose of having the mold fill better/sprue cut more easily- Or at least I am under the impression it gives these benefits. I ran the boolits through a sizer (Lee .224) and it offered very little resistance. Despite this, I'm apprehensive- I wanted hard, but maybe I went too hard? I'll listen to my gut and air on the end of prudence and go plain-jane Zinc.

I'll just wait a week before I can get more propane and cook up some Zinc. Maybe after I play with Zinc boolits for a while I might play with hardening those...If needed.

I'll look at it in a positive light- I made a small batch of an awesome alloy...Maybe I can mold what I have into something useful.

Thompsoncustom

02-09-2013, 06:33 PM

Bottom line, I'd start very light when loading Zamak bullets, or better yet try driving one through the bore with a rod (largest size steel that will fit, protected from bore contact, since it's probably going to flex) to compare effort to that needed for a hard cast boolit or pulled steel jacket pill.

That's a good idea I never thought of that when I was shooting Zamac tho sizing wasn't difficult so I would imagine pushing it through the barrel would be either. My recoveedr Zamac bullet seemed to engrave the bullet with rifling the same as FMJ bullet do.

osiek

02-10-2013, 09:52 AM

is there not some Zinc in wheel weight led? And if so is there a problem casting these Led/Zinc highbred bullet? and if so how do you separate the two materials once they are in ingot form?

Thompsoncustom

02-10-2013, 11:21 AM

Well lead can absorb up to 2% zinc after that you start to get the oatmeal effect and no there is no problem running them with zinc in it. You can get it out a few different ways the easiest being just slowly heat the lead alloy and the lead, tin, and everything but the zinc should melt then you can scoop out the zinc and/or flex with some sulfur.

I'll Make Mine

02-10-2013, 04:16 PM

That's a good idea I never thought of that when I was shooting Zamac tho sizing wasn't difficult so I would imagine pushing it through the barrel would be either. My recoveedr Zamac bullet seemed to engrave the bullet with rifling the same as FMJ bullet do.

Sure, you can shoot bullets that are way too hard and they'll still engrave (Zamak at BHN 100 is still softer than barrel steel at BHN 200-500), but if they take a great deal more pressure to engrave than the bullets we usually load, you may see excessive pressure -- hence my recommendation to start with absolute minimum jacketed load data. Don't forget, the Zamak will also be much longer than a jacketed lead bullet the same weight, so there's more contact area, hence more friction even after engraving is completed. It could well take ten times the pressure to engrave Zamak compared to wheel weight alloy -- which, if you use data above the mininum published load, might well result in the barrel or receiver giving before the bullet engraves (especially with a progressive burning powder).

If you want a really light bullet, you might actually be ahead to machine a bullet from conductor grade aluminum wire, rather than cast in Zamak or even pure zinc; aluminum is lighter still, and conductor grade (= 99.9% pure) is no harder than pure zinc, but more ductile. Yes, aluminum bullets have been done in the past with poor success -- for the same reason zinc hasn't been common until the current lead-free requirements various places: a heavier bullet does a better job at most of the things we want bullets to do.

is there not some Zinc in wheel weight led? And if so is there a problem casting these Led/Zinc highbred bullet? and if so how do you separate the two materials once they are in ingot form?

The lead alloy in lead wheel weights has effectively no zinc -- it's lead and antimony, possibly with a trace (.1% or so) of tin for fill out, and might also have a little arsenic or bismuth, depending where the scrap lead came from to make it (wheel weights these days are like boat keels and diver's weights, i.e. anything dense and cheap that melts at a reasonable temperature). Zinc gets into smelted wheel weight via missing zinc weights when sorting; the molten lead alloy will dissolve up to about 2% zinc by weight even at a hundred degrees below the melting point of zinc.

Thompsoncustom

02-10-2013, 09:07 PM

hmmm I think I need to do some testing on the force is takes to engrave zamac bullets vs FMJ bullets as I don't think there is a whole lot of difference.

What do you think of taking a barrel, c clamp, torque wrench and a steel rods to do the testing? I could set the bullet in the chamber with the steel rod behind it then put the c clamp on the end of the barrel and the steel rod and use the torque to see how much force it takes to push each bullet in a inch or two.

I'll Make Mine

02-11-2013, 09:28 PM

I think the thread on the C clamp will give too much leverage, unless your torque wrench reads out in single inch-pounds. I also think you might get variation from one run to the next based on the state of cleanliness and lubrication of your clamp threads.

Since we're after engraving force, not barrel friction (though that's a concern, too, engraving force is where Zamak is going to cause trouble, IMO), you could use a take-off revolver barrel, cleaned and lubricated before each trial, and Zamak bullets sized to match the diameter of your jacketed control pills. Set up the bullet standing vertically aligned in the forcing cone (barrel muzzle down in a vise) restrained by a slightly oversize tube; put a rod on top of the bullet and a lever (horizontal or at same inclination for all trials, please) and measure how much weight you have to hang on the lever to move the bullet until it's fully engraved (ideally, the Zamak and controls will have similar bearing length, which will make the Zamak lighter). No need to back out the actual force on the bullet, as the weight on the lever will be proportional to engraving force, and we're after which is higher and by what ratio, not any absolute figures.

johnnybar

02-11-2013, 11:16 PM

Zinc is hard and brittle until about 220F at which it becomes malleable. It becomes brittle again around 410F. As you already know, annealed steel, copper, brass, and lead are all very malleable at room temp. IIRC, zinc is also very hard on melting pots. It will eat a Lee pot in no time. Hardness is only one aspect of metalurgy. What happens to a relatively soft metal when force is exerted upon it? Does it give by easily flowing and displacing or does it fracture and displace. Zinc is the latter more so than annealed steel, gilding metal, and lead. a bar or wire of each being bent will tell you why zinc is a poor choice. In addition zinc fumes are very bad for the lungs if you happen to over heat it in a smelting job.

Raven_Darkcloud

02-12-2013, 11:50 AM

so, is zinc oxide harmful?
Zinc oxide is in many common products you use. Only if you have an allergy will it be an issue.

johnnybar

02-12-2013, 12:45 PM

Zinc oxide is in many common products you use. Only if you have an allergy will it be an issue. Welders, in addition to brass and bronze foundry workers are very familiar with it and would beg to differ with your comparison to diaper creme or white sun block commonly applied to the skin of the nose. I believe you are letting route of exposure have no importance in your statement. That kind of reasoning would lead me to believe that I can breathe water. When zinc or one of its alloys is burned, melted, or heated in air to greater than 930 F, oxide is formed as a fine dispersion of dry particles. The inhalation of these causes metal-fume fever. This disease has been called zinc fever, zinc chills, Spelter's shakes, glavo, and metal shakes. I have had the somewhat unique perspective of welding my way through college expenses then spending 32 years in the medical profession. I have seen both sides of exposure to zinc fumes. It exists unequivocally. Lots of ventilation and remember that even staying upwind of your smelter can cause eddy swirls directly back into your face. Upwind and a little to one side is best...be careful.

johnnybar

02-12-2013, 01:28 PM

is there not some Zinc in wheel weight led? And if so is there a problem casting these Led/Zinc highbred bullet? and if so how do you separate the two materials once they are in ingot form?

If it won't shoot decent...cast some pretty corn cobs or fish to hang on the shed wall. :-)

Thompsoncustom

02-12-2013, 02:38 PM

Thought I would add this as I just remembered I had it.
61057
The photo is of a zinc/alum bullet that went head on into the side of my steel bullet trap. Gives you a picture of the engraving on the bullet tho doesn't help with the force required.

johnnybar

02-13-2013, 01:01 PM

You can get an idea of required force by running a #2 alloy slug and a zinc or zinc alloy slug of equal size through a lubrisizer or a Lee sizer in a O frame press. Use a spring scale to pull the handle or stand on a bathroom scale (non-digital) while pulling down on the sizer's handle to get a rough estimate of force.

Thompsoncustom

02-15-2013, 07:00 AM

I like the scale Idea but I'm having problems finding a FJM copper bullet big enough to need sized. I have my sizer (lee push through) bored out to size at .3565 and I can't find a FMJ bigger the .356 I started by looking at all my 9mm HP boolits I reload and most are under 355 so yesterday I bought a bag of .38 cal 130gr flat point boolits and when I got them home they also measure 356, so I thought it might be my calipers but I double checked them and there good so anyone have a idea on a bullet that's say 357 or .358

jabilli

02-15-2013, 06:27 PM

What would be useful for testing- 61344

I got propane today- I'm prepping another melt to play with. :-)

Eagle66

02-15-2013, 08:43 PM

so, is zinc oxide harmful?

If you've been casting zinc, drink a big glass of milk when you're finished. That's long been a practice with welders, zinc foundrymen, etc. They say it will head off the "Metal Fume Fever".

http://en.wikipedia.org/wiki/Metal_fume_fever

If your melt starts to put out white smoke, reduce the temperature and ventilate the area better. And don't forget the milk.

BAGTIC

02-16-2013, 04:26 PM

Governments do care about barrel wear. Barrel in artillery are much more expensive that the savings in casts between copper bands and iron bands. Furthermore the ammo is made in home side factories where materials are comparatively more readily availability. When a artillery barrel wears out in a wartime scenario it is a long way from home and replacements and it often wears out at a critical time.

I can be about as cynical about the government as anyone. Wasteful? Perhaps. Stupid? They aren't.

BAGTIC

10-13-2014, 09:34 PM

Grooves, lubing and crimping, generate drag. With low BC handgun bullets at short range it probably would not make much difference. If ones wanted the best possible BC from an already light bullet it could make a big difference down range. Also the easiest way to make zinc bullets is by die casting and the simpler the bullet shape the easier the casting.

BAGTIC

10-13-2014, 09:47 PM

Her is a list of foods high in zinc. http://nutritiondata.self.com/foods-012124000000000000000-w.html?maxCount=57e Zinc is and essential nutrient for humans and many crops such as pecans. It is the basis for many ant-fungal medicines including the old standard calamine lotion.

Hogtamer

04-16-2016, 08:25 PM

pI've put a lot of water over this dam in the last year for a Zn/Al alloy (Zamak 3) shotgun slug. Short version, Tom at Accurate molds cut me a mold that casts a .731 / 580 gr zamak 3 slug (96% Zn, 4% Al) for full bore 12 ga that I move along in a pressure tested 3" load @ 1700fps. The same mold casts 775 gr in Pb and no way I could come close to that velocity with that much weight. 4" group @ 100 yds. Very successful project and I've got enough loaded and put away in case I ever need to stop a truck. Found most of the objections in these thread without merit. Yes, it takes about 825* to cast but fill out no problem, engraving no problem, takes longer to set in mold but sprue cutting no problem with Tom's mold. 166386 Lube grooves only to reduce bearing surface to about 32%

Ricochet

04-21-2016, 07:24 PM

For those who wish to experiment:
http://www.rotometals.com/product-p/zamak-3-ingots.htm

For those interested in zinc washers for Prot-X-Bore boolits, Hawk Bullets will sell them to you. You will have to call or E-mail them, the online order link is obsolete, but they confirmed to me a couple of weeks ago that they can provide them. They sell equipment for swaging Prot-X-Bore bullets.
http://hawkbullets.com/Prot-X-Bore.htm

If you want to experiment with the idea that zinc based bullets will "sherardize" your bore and entirely prevent leading, you can make gas checks of either the plain base or standard type out of pure zinc sheet, which is widely sold for interior decorating purposes. A quick look around turns up .006" and .020" as common thicknesses that I believe could be used. There are kits sold to make your own checks. You might convince one of the boutique check makers to do it for you if you supplied the zinc sheet. A few zinc boolits, base washers or gas checks aren't going to poison the berm for lead miners, either.