Zinc bullets, why harder on bore than copper?

[jabilli]

Oh hahah Lightbulb Thanks

[jabilli]

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 ) may be the best option. Anyhow....Thought that might be something people might be interested to know.

[Thompsoncustom]

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.

[oldpara]

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.

Ain't that the truth !
I've been playing with stuff so much I don't have time for REAL shootin.

[jabilli]

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) >< 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/286...an-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]

PICTURE TIME!


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.


A picture of the air bubble craters.


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.


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)


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.


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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.