Questions about zinc

[Jim]

I know not to mix it in my melt, OK? Has anyone ever successfully made boolits from zinc? I just found a large supply of it and was wondering if it could be done. The melting point is not out of range and I thought I'd try it from a pot with a ladle.

Any feedback?

[DLCTEX]

I think it calls for higher casting temps than we can get with our equipment ( read this somewhere) and was said to call for injection molding to get casts without flaws. It would also call for molds made to cast the size you need as it would make much lighter boolits, and cooling time between casts would be excessive. Then there are questions about brittleness. It may can be done, but at what cost? That said, it doesn't hurt to experiment, and who can say what a 50-50 mix will do, and cooling on a wet sponge can shorten cooling time a lot. I do know that it doesn't take much zinc to require much higher casting temps, but a little zinc in the mix still casts good boolits. DALE

[docone31]

I would lean more to 75% lead, 25% zinc.
Maybe lighter.
The key is to not have to get into exotic casting.
Who knows, it might do well.
I would make small batches, weighing the mixture and alloy components.
This would be an interesting issue.
Will take more heat though.

[Jim]

The periodic table says the melting point of zinc is 787 and lead is 621. So we got less than 200 degrees difference. I know for a fact I can generate that kind of heat in a pot over a propane burner. If I can get zinc and lead to melt and bond in a liquid state, I MIGHT be able to cast boolits with a much higher BHN.
More questions:
Might the alloy be hard enough to negate the need for lube?
If I get "zincing" in the barrel, how would I get it out?

I love opening worm cans.

Feedback?

[docone31]

I can see you do. I love it too. I learn a lot.
I would use the lube grooves. I think the lube acts as a sealant also.
If wheel weight was used with zinc, with the addition of tin, I believe a very hard casting is possible.
Would this work?
Will the rifleing engrave?
Can we expect jacketed velocities with reliability?
I sure learned some lessons with high power cast loads. 10ft accuracy is one thought that comes to mind.
I would though, really like to see someone experiment and get positive results. I do not have the facilities, time, or anything I can put zinc in without contaminating my prime melt.
Lets see what this thread produces.
I wonder if the wheel is being re-invented.

[Harry O]

There was an article on casting zinc in an old handloaders annual. I posted about it here before. You need a pot that will go to a higher temperature than ordinary lead melting pot. You need to have a mould with a larger hole in the sprue plate. They have to be made to EXACT diameter because there is no machine now on the market that can size them down. The bullets were lighter than they would have been in lead so they could be loaded to higher velocities.

What I have been wondering is why not embrace the future instead of fighting it. Especially since California is now banning lead (or partial lead) bullets and since cars are going to zinc wheelweights instead of lead.

[felix]

The gun twist must be on the fast side. The Swede comes to mind. ... felix

[Jim]

[QUOTE=Harry O;375554 They have to be made to EXACT diameter because there is no machine now on the market that can size them down.

I have a 5 ton hydraulic sizing press. I have sized solid copper bullets down several Ks.

[rusty marlin]

Where zinc becomes desirable as a projectile is for live cannon fire. It has a very similar mass to iron. So a cannon ball made from zinc will have a similar breech pressure as one made from iron, which is signifigantly less than the same one made from lead. Also the old gunnery charts are much closer with a zinc projectile.

Zn, .24#/in^3
cast Fe, .25-.26#/in^3
Pb, .41#/in^3

[44man]

While pure zinc needs more heat, once in an alloy with lead, tin, etc, the melting point comes down. Just like antimony in an alloy. I melt pure antimony into lead, tin at 600*. With a good flux, zinc will also melt in at a low temperature but without flux you can remove the zinc slush from the top of lead at 600*
Pure zinc would probably shoot OK but I don't want any mixed in my lead.

[felix]

Based upon the density shown above, it would make the twist requirements for zinc approach double that of lead. Being that iron and zinc weigh the same, what does an iron projectile need in twist, say for the iron-shooting cannons? Not cannon balls, but bullets with the same appearance with the difference only in scale? ... felix

[rusty marlin]

a 155 howitzer has a 1:20 twist. Does this help?

[only1asterisk]

The twist for a zinc bullet would be the same as the lead bullet from the same mold.

David

[rusty marlin]

Felix, the formula for twist rate doesn't contain a mass factor. Its dependant on length and diameter.

If you want a Zn projectile the same weight as the Pb one but the same diameter, then, yes, the twist would need to be about twice as fast.

Or... did I miss something?

As for Zn cannon balls... right from the archives...http://castboolits.gunloads.com/showthread.php?t=1082

[felix]

The required twist is proportional to the amount of resistance needed to thwart the elements from gun to target. In outer clear space you'd need next to zero twist for any kind of projectile. ... felix

[NoDakJak]

That article is also included in the book titled "The Art of Bullet Casting from Handloader & Rifle magazines 1966-1981. The article is titled "Zinc Bullet Police Loads" and was written by Leon Day. Very interesting article. He was using Lyman mold 358425 and producing a 68 grain wadcutter. Test gun was a four inch Charter Arms 357 Target Bulldog. The load was 9.5 grains of Bullseye i n a 357 case and average velocity was 2,065 fps. He said that he sized the slugs by using a hammer and punch and drove them thru a Lee sizing die. The bullet does not require lube and no leading occurred. The alloy he used is called ZAMAK #3. Hmm! Isn't that what they use to make cap pistols? One helpful tip that he gives is to not contaminate the alloy with lead! He also states that hardened zinc is to hard for the sprue plate to cut and it must be operated almost instantly before it can harden. The weight is only 66% that of lead and the bullet slows very quickly. Velocity is listed as 2,000 fps at 25 yards, 1,450 at fifty and 840 at 100 yards. Energy drop is even more dramatic. 604 footpounds at 25 yards, 327 at 50 yards and 189 at 100. At three hundred yards velocity has dropped to 349 fps an 18 foot pounds. Neil

[felix]

And that is a whale of a lot of resistance afforded by the elements: 2000 fps at muzzle down to 350 fps at 300 yards! I am surprised they could hit the target at 300, the target being some kind of chrono dealie. I sure wouldn't try to go through the little triangle at that distance for fear of some little gust of wind somewhere down the line. ... felix

[rusty marlin]

You've never set a steel plate infront of a chrony? I used to "armor" my buddies when we shot at extended range by driving a stake in the ground and hanging a gong on it, nothing but the sky screens poking out from the view at the bench.

[Jim]

This is the kind of feedback I like. The issue of the zinc hardening beyond being cutable with the sprue plate is something I had not thought about. Did Leon Day explain what happens to the lead/zinc mixture? Obviously, there's a reason he suggests not alloying lead and zinc. On the other hand, I've read where it has been done with success.
My thoughts now are blending the two metals at different ratios until a suitable hardness is found, but still soft enought to be able to cut it at the sprue.

I'm still unpacking from my recent move and where my loading/casting shop is gonna be, there are stacks of boxes. I expect it'll be a month or better before I get set up. On top of that, it's hot as blazes here and the afternoon sun shines in the front door of the garage where I'll be casting. I fully intend to research this lead/zinc thing, but it'll be a while yet. I promise I'll be posting as I go once I get started.

[yondering]

Just the other day I was investigating some mystery metal I had, and found it to be zinc, based on melting point, weight (density), etc. To check density, I cast up a few bullets, and had no trouble cutting the sprue. I cut the sprue within 5-10 seconds of the sprue puddle frosting over.

[yondering]

I used to "armor" my buddies when we shot at extended range...

It's amusing what a difference an apostrophe makes, between making your buddies wear armor downrange, and protecting your buddie's chronograph. :mrgreen:

[Jim]

Just the other day I was investigating some mystery metal I had, and found it to be zinc, based on melting point, weight (density), etc. To check density, I cast up a few bullets, and had no trouble cutting the sprue. I cut the sprue within 5-10 seconds of the sprue puddle frosting over.

Yondering,
Can you be SURE it was zinc? I'm not challenging, just asking. If so, that's good news.

[yondering]

Yondering,
Can you be SURE it was zinc? I'm not challenging, just asking. If so, that's good news.

99% positive it's zinc at this point. Others seem to agree, see my other thread recently called "Ingots marked "S" - zinc? "

It definitely took more effort to cut the sprue, but not that bad. I did have to use my plastic mallet instead of just thumb pressure, but I used to do that all the time with lead, too.
I didn't try letting it cool too long; that might have a big effect.

[rusty marlin]

It's amusing what a difference an apostrophe makes, between making your buddies wear armor downrange, and protecting your buddie's chronograph. :mrgreen:

Yeah yeah yeah.

We ingineers don't need no inglish. :mrgreen:

I usually catch stupid mistakes like that... about a week after everybody has looked at it and thought, "What doofus. Can't he use correct grammer?"

[Harry O]

I found the information I had on zinc casting again. Here it is:

It is the 12th Edition of Handloader's Digest. The article is "Shooting Zinc in Big Bores". He had .45 moulds that he used in the 45-70 and a .458 Magnum. In addition to the things I mentioned above, it says:
1) Velocities, and trajectories are radically different from lead or jacketed bullets. Re-zeroing is needed. The weight is 62% that of a lead bullet the same size. Velocity was higher. Nothing was said about twist or that they had problems with it.
2) Sizes should be the groove diameter to 0.001" smaller. NEVER larger. Again, they were unable to size them except by lathe-turning.
3) Lubrication was not necessary (like jacketed).
4) A gascheck was not necessary.
5) DO NOT mix loading equipment. Use either zinc or lead, don't switch from one to another. Mixing lead and zinc makes it thicker (more viscous) than either is alone. If a bottom pour pot is used, it must run a lot hotter than lead ones and must have a larger outlet.
6) Water quenching is not necessary.
7) DO NOT HUNT with zinc bullets. Because of the light weight, they do not penetrate well, nor do they retain velocity. (Practice? Paper punching?)
8) Veral Smith made the moulds for this guy. They were his special iron, with a 50% larger sprue plate hole, and bevel base. It was a single cavity mould. He did not think that a double cavity would work.
9) Because of the lighter weight bullets, faster powders are usually needed.
10) Accuracy was sometimes good (1-1/4 MOA), but sometimes difficult to obtain. Crimping hurt accuracy. Neck tension was critical. Proper fillout of the mould was VERY important. Interestingly, only one of the bullets he has pictured has no lube grooves.
11) There is loading data in the article. It is completely different from anything I have seen with conventional bullets.

[Jim]

Harry,
I'm just now getting back to this thread. Thanks for posting that. Man, this really has my interest piqued.