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twud
Advanced Member



USA
2092 Posts

Posted - Nov 03 2009 :  18:31:29  Show Profile Send twud a Private Message  Reply with Quote
What is gilding metal? Can I asssume it's some type of copper alloy?

NRA Life Member

If a man is alone, deep in the woods, and there is no woman to hear him is he still wrong?

Smokeless
New Member

14 Posts

Posted - Nov 03 2009 :  20:16:30  Show Profile Send Smokeless a Private Message  Reply with Quote
quote:
Originally posted by twud

What is gilding metal? Can I asssume it's some type of copper alloy?

It is basically the build up of the bullet jackets left in the bore from friction. Combine that with heat and pressure and you have gilding.
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Evad
Advanced Member



USA
1333 Posts

Posted - Nov 03 2009 :  20:16:41  Show Profile Send Evad a Private Message  Reply with Quote
Twud,
Gilding metal is a copper alloy, comprising 95% copper and 5% zinc. Technically, it is a brass. Some manufactures may use a little different alloy, but it is basically the same. Hope this helps.
Dave

I never met a gun I didn't like.
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steve4102
Advanced Member

USA
932 Posts

Posted - Nov 03 2009 :  20:34:20  Show Profile Send steve4102 a Private Message  Reply with Quote
quote:
Originally posted by Evad

Twud,
Gilding metal is a copper alloy, comprising 95% copper and 5% zinc. Technically, it is a brass. Some manufactures may use a little different alloy, but it is basically the same. Hope this helps.
Dave



Yup, and many of our jacketed bullets are covered in Gilded metal.
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Wolfgang
Advanced Member

3379 Posts

Posted - Nov 03 2009 :  21:42:41  Show Profile  Visit Wolfgang's Homepage Send Wolfgang a Private Message  Reply with Quote
Evad is close, actually there are dozens of different alloys known as "guilding metal" and it does not necessarily have anything to do with bullets. Bullet jacket material also varies greatly including those jackets termed as "guilding metal". Technically, Cu/Zn alloys are not in the yellow "brass" catagory unless the Cu content is under 75% and "red brass" requires a Cu content under 93%.

As the term "guilding metal" applies to bullet jacket material, it can be any variety of alloys such as;
Cu87/Zn12/Sn1
Cu90/Zn10
Cu93/Zn7
Cu93/Zn6/Sn1
Cu95/Zn5
Cu95/Zn4.5/Sn0.5
Cu95/Ni5
Cu97/Zn3
Cu98/Zn2
Cu98/Ni2

Cupronickel is also sometimes incorrectly identified as guilding metal. Cupronickel alloys also vary greatly such as;
Cu75/Ni25
Cu80/Ni20
Cu85/Ni15
Cu90/Ni10
Cu90/Ni9.8/Ag0.2

This is not a complete list as the proportions of the alloy are generally tailored to the specific application of the bullet being produced. There are also a variety of steel alloys that are used for bullet jacket material - the most common of these is incorrectly called "bi-metal" but this is not an "alloy" but rather it describes the plating or washing process of the soft steel bullet jacket material with a corrosion resistant alloy that is normally of a copper/zinc, copper, nickel or zinc composition. In addition to all of these, pure Cu is also somewhat common jacket material on custom and premium bullets. Brass and bronze alloys are also used occasionally, both being limited to non-expanding or very limited expansion bullets and fixed or rotating bands on specialty projectiles. The major element of bronze is copper, second major element is tin and additional common but lesser volume elements are phosphorus, manganese, aluminium, lead and silicon. Copper is also the primary element in brass alloy with the second major element being zinc and the additional elements being iron, aluminium, silicon, lead and manganese.


Carry the battle to them. Don't let them bring it to you. Put them on the defensive and don't ever apologize for anything."
Harry S. Truman
mark@fire-iron.biz



Edited by - Wolfgang on Nov 03 2009 21:50:19
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sonnyboy
Senior Member



USA
358 Posts

Posted - Nov 04 2009 :  05:05:51  Show Profile Send sonnyboy a Private Message  Reply with Quote
Hey Wolfgang:
Tell me my friend, is cupronickel the same thing as an old name I read many years ago, "German Silver"?

Happy Shooting
sonnyboy
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Wolfgang
Advanced Member

3379 Posts

Posted - Nov 04 2009 :  07:56:21  Show Profile  Visit Wolfgang's Homepage Send Wolfgang a Private Message  Reply with Quote
quote:
Originally posted by sonnyboy

Hey Wolfgang:
Tell me my friend, is cupronickel the same thing as an old name I read many years ago, "German Silver"?

Happy Shooting
sonnyboy



No. German silver alloy used for gun parts and musical instruments normally has a zinc content such as;
Cu60/Ni20/Zn20
Cu65/Ni18/Zn17
Cu55/Ni40/Zn5
Cu50/Ni40/Zn10
Cu50/Ni49/Zn2
Cu68/Ni31/Zn1
Cu72/Ni18/Zn10

Or it can often be straight Cu/Ni alloys such as;
Cu55/Ni45
Cu60/Ni40

Depending on the application the alloy may change considerably adding such elements as; iron, antimony, tin, lead, or cadmium.
Cu88.6/Ni10/Fe1.4
Cu69.4/Ni30/Fe0.6
Cu88.2/Ni9.5/Sn2.3
Cu70/Ni28/Sb1/Sn1

When I use GS for gun parts like trigger guards, buttplates and sights or ram rod pipes and patch boxes on muzzleloaders, I normally give it a harder temper - the nice thing about using GS is that it can be tempered hard without becoming brittle like brass. When used for inlays and wire work, it doesn't tarnish like stirling silver and can easily be done with a semi-satin, satin or brush finish that still looks good (especially on dark woods like walnut) but doesn't create unwanted glare.


Carry the battle to them. Don't let them bring it to you. Put them on the defensive and don't ever apologize for anything."
Harry S. Truman
mark@fire-iron.biz


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Evad
Advanced Member



USA
1333 Posts

Posted - Nov 05 2009 :  01:18:58  Show Profile Send Evad a Private Message  Reply with Quote
Hey wolf,
I was not trying to be as technical about as you were.
Dave

I never met a gun I didn't like.
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Wolfgang
Advanced Member

3379 Posts

Posted - Nov 05 2009 :  05:30:49  Show Profile  Visit Wolfgang's Homepage Send Wolfgang a Private Message  Reply with Quote
Dave,
No offense intended. I was just pointing out the differences in the alloys because the generic terms like "guilding metal", "brass", "German silver" and "cupronickel" simply don't tell the whole story. Some years ago there was a lady from southern NY making custom premium hunting bullets with cupronickel jacket material. She did not say what the exact alloy was that she was using but she quickly built a reputation for having excellent quality bullets. It wasn't long until two imitators tried cashing in on her success and soon there were complaints about excessive fouling and damaged bores from "cupronickel" bullets and soon, no one was buying any bullets with cupronickel jackets. What happened is that the imitators, as is all too common, bought the cheapest cupronickel they could find. One happened to be an alloy blend containing high levels of iron and manganese that work-hardened, by the time the bullets were swaged, they were extremely hard causing rapid barrel wear. The other imitator was using an alloy with a high level of aluminum and iron that deposited heavy fouling. Although there are very few custom bullet swagers around anymore, it pays to know what you're buying - besides, there was just a big stink over hard-cast rifle bullets purchased at gunshows in VA being made primarily from zinc and fragmenting on impact.

From my standpoint, I need to know the alloys for two primary reasons -
1- Different alloys have different colors. No matter what the primary ingredient of the alloy is, each alloy has a different color. You can look at five different strips of German silver alloy individually and not notice any difference in color - however - if you put them side by side you'll see the different range of color. Brass is even more noticable especially where the two most common casting alloys are used to make gun parts are different enough for one to appear with a bright gold/brass color and the other has a definite reddish color.

2- Different alloys have different mechanical properties and the ability to harden or anneal the alloy at will as well as if the alloy is prone to work-hardening can make a huge difference in it's viability for use in the intended application.


Carry the battle to them. Don't let them bring it to you. Put them on the defensive and don't ever apologize for anything."
Harry S. Truman
mark@fire-iron.biz


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Evad
Advanced Member



USA
1333 Posts

Posted - Nov 05 2009 :  23:56:23  Show Profile Send Evad a Private Message  Reply with Quote
Wolfgang,
No offense taken. I just don't like to type very much any more, it makes my hands hurt. You always give very good explanations on anything you type about, and I enjoy reading your posts.
Dave

I never met a gun I didn't like.
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Wolfgang
Advanced Member

3379 Posts

Posted - Nov 06 2009 :  00:48:32  Show Profile  Visit Wolfgang's Homepage Send Wolfgang a Private Message  Reply with Quote
Dave,

Drop me an email and I'll explain some excercises you can do that may help your hands. I have severe bi-lateral carpal tunnel with nerve damage. No kidding, just some stretches that make you look funny but they really work. mark@fire-iron.biz


Carry the battle to them. Don't let them bring it to you. Put them on the defensive and don't ever apologize for anything."
Harry S. Truman
mark@fire-iron.biz


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ten2six
Advanced Member



USA
3569 Posts

Posted - Nov 06 2009 :  15:14:05  Show Profile Send ten2six a Private Message  Reply with Quote
Wolfgang,

With so many types of guilding metal, do you know if different manufacturers use different types in current manufacture brass? If so, is there a longevity benefit to any of them?

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku
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Kansas Ed
Advanced Member



USA
1210 Posts

Posted - Nov 06 2009 :  16:50:57  Show Profile  Visit Kansas Ed's Homepage Send Kansas Ed a Private Message  Reply with Quote
Wolfgang,
After the heat treat process with GS, does the color change?

Ed

Are we there yet???
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Wolfgang
Advanced Member

3379 Posts

Posted - Nov 07 2009 :  07:33:17  Show Profile  Visit Wolfgang's Homepage Send Wolfgang a Private Message  Reply with Quote
Okay, I got one question via PM so I'll start with that one...
quote:
Why is gilding metal superior to just copper in jackets. Some of the bullet manufacturers tout it like it's better in some way.
Why are J4 jackets considered superior, especially amoung the benchrest crowd.


Can you say "sales hype"? Right off the top of my head I can likely name more than a dozen high-copper alloys that will function quite well as general purpose expanding bullet jacket material. Add to that at least another dozen copper and non-copper alloys that also function great too. Bullet construction is not limited to simply figuring out a shape, it is the whole package from end to end and thus requires mating properly selected alloys with properly engineered designs. Since there is no listing of "J4" alloy in any of the standards for high-copper alloys, nor any other alloy for that matter, one can safely assume that it is purely a fictional designation applied to a common gilding metal alloy that is more likely than not to be common Cu95/Zn5 likely with some trace elements as a pure bi-alloy would be excessively expensive. Zinc and other alloying elements are added to copper to change its mechanical properties, more often than not, the common 95/5 alloy is selected because it's readily available and used in many different industries with the electrical industry being the biggest user. 95/5 is known as one of the basic alloys providing a good balance between work hardening and increasing the ductile strength and corrosion resistance of copper without having a great detrimental effect on the heat & current carrying capacity of the finished product. Just a little FYI, nickel is also alloyed in low proportion to copper such as the Cu95-99/N1-5 alloys that retain the common copper color but greatly increase the strength and abrasion resistance again without having a detrimental effect on the electrical properties (notable that some of these alloys also contain trace and additional alloying elements like aluminum, magnesium and phosphorus.

Without going to novel-length here, the process of forming the bullet jackets imparts a certain amount of work hardening to the alloy and the key is to get the hardness desired without getting it so hard that it becomes brittle and thus is why 95/5 is well suited to the application. The harder the jacket material, the thinner it can be made without loosing its ability to control expansion. Likewise, a softer jacket alloy can easily be used with a harder alloy lead core to achieve the same exact after-impact results. This is not commonly done because this process requires tighter alloy and process controls as well as higher final forming pressures that would slow and increase the cost of production. Also consider the fact that you're working with a certain level of tolerance in all aspects of the shooting game from bore & groove diameters to loading dies and the bullets themselves. When you buy a box of bullets, you're buying bullets that are made to a "nominal size" not an "exact size" - buy ten boxes from ten different lots of any caliber bullets and measure each one accurately to the 0.000X position and you'll find considerable variations in diameter alone. Accurately weigh them to the 0.0X position and you'll also find considerable variations in weight. By "accurate weight and measure" I mean you must use tools that allow for such accuracy, the common calipers and balances sold for reloading purposes quite frankly suck for tight accuracy, the typical digital reloading balance is not anywhere near accurate enough for this purpose, a "half-decent" digital balance will set you back $800, a "good one" will lighten your pocket by almost $2k, and a "real good one" starts around $3.5k so don't expect reasonable weight accuracy from anything under $500 and that doesn't come with a certification guarantee. Same with measuring tools, the $25-30 calipers will suffice for non-critical work but if you really want decent repeatable accuracy, prepare to drop at least $500 for vernier caliper/micrometer. Quite honestly, there's no point in doing such, because we fall back on the allowable level of accuracy for a given task - however - if you're weighing & measuring bullets with what's considered "half-decent" tooling for reloading operations and you're seeing variations, you know for sure that you're playing with much wider tolerances than you expected to see.

What this all boils down to here is that companies using a slightly harder jacket material can make claims such as; less fouling, better consistency and so forth because the bullet is not responding to every little quirk of the loading and shooting operation. Whereas a pure Cu jacket will produce more fouling in a bore that isn't smooth enough, the harder gilding metal jackets will allow more blow-by before they'll start gas-cutting and will pass through rougher bores without depositing as much fouling ... the same can be said for jackets made from other alloys as well so no, there is no definable advantage to using a particular alloy for bullet jackets to be used for general purpose applications.

quote:
With so many types of guilding metal, do you know if different manufacturers use different types in current manufacture brass? If so, is there a longevity benefit to any of them?


Typical cartridge brass is 68.5% - 71.5% copper, 29% - 32% zinc with the balance made up of the typical trace elements Fe & Pb. Again, just as with bullet jackets, the particular application is what determins the viability of a particular alloy being better suited to the use. Higher Fe content makes for harder brass that will often see shorter life spans if it is subjected to FL or otherwise excessive size changing operations. Ni plated brass is the most common that is known for sizing stress failure attributed to excessive/repeated sizing. Higher Pb content will tolerate sizing better but will also pressure deform and stretch more. For instance, UNS C33000/MIL T-46072 is a "leaded" brass alloy containing 65-68% Cu with 0.25-0.7% lead and up to 0.07% iron and zinc as the balance. This alloy has excellent cold working properties but a "poor" rating for machinability making it a great choice for low-med pressure rounds that are commonly subjected to repeated sizings. On the other hand, alloys with a higher hardening alloy content can also be better suited to high pressure applications where the amount of sizing is limited. The particular alloys used for cartridges varies greatly and more often than not, the primary concern to the mfg is not longevity but the cost of mfg'ing. If the brass must be repeatedly subject to annealing operations at different stages of forming, this greatly increases the cost whereas if the chosen alloy requires only one or no annealing operations during the forming process, it saves the company a lot of money and quite frankly they don't care if you don't get any reloads out of it because all that matters is that it survives the first firing with some room for error.

quote:
After the heat treat process with GS, does the color change?


Yes and no. (I sound like a congressman there don't I?) LOL At the risk of sounding like a broken record, it depends on the particular alloy, manner of heating & cooling, length of time held at temperature ....... If you use too high of temps or too long of an exposure, you can cook the alloy changing both color and properties. Open flame heating can surely cause exterior heat/scorch discoloration as well as alloy discoloration from cooking it. Absolutely it is best to anneal GS in a vacuum or atmospherically controlled furnace and quench in de-min/pure distilled water or other inert quenching medium but for most of us, that just isn't a feasible process so the alternative is to watch your temperature and exposure time carefully staying within the known parameters of the given GS alloy and then following-up with the necessary surface cleaning & polishing process. Can you intentionally change the color of GS, yes you can and no I have not studied up on the different processes required to obtain given effects because it is an art within itself.


Carry the battle to them. Don't let them bring it to you. Put them on the defensive and don't ever apologize for anything."
Harry S. Truman
mark@fire-iron.biz


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dtknowles
Senior Member

201 Posts

Posted - Nov 07 2009 :  22:26:58  Show Profile Send dtknowles a Private Message  Reply with Quote
About color changeing. I found some brass that had laid in the grass for a long time. It had darkened and had a very slick hard oxide layer. I don't know what the grass had to do with it but the color and surface finish was different from brass that was laying on the bare ground. I prized this brass because of the uniform color and hard slick surface. Kind of like dark nickel only harder to scratch.

Tim
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Wolfgang
Advanced Member

3379 Posts

Posted - Nov 08 2009 :  06:41:18  Show Profile  Visit Wolfgang's Homepage Send Wolfgang a Private Message  Reply with Quote
Tim,

Different chemicals create different effects and while it's anyone's guess as to exactly what the affect of the grass was, it can safely be assumed that the oxygen rich environment was beneficial. Grass is like most all other green plants, they eat Co2 and discharge O2 as a waste product creating the O2 rich micro-atmosphere. Most grasses are good at trapping contaminents too, either on the blades or within the thatch layer plus there are also the byproducts of organic decomposition too.

The "black coating" is an oxide layer, the metal's way of self preservation that is activated by the presence of certain chemicals/elements within the environment. This process can be seen with most metals, rust blue on iron is good example because it is the process of converting the common destructive rust into the preserving iron oxide layer. If you've ever dug an old bullet out of the backstop, you'll find it encased in a self-preserving oxide layer which is why the claims of metalic lead like bullets/shot/wheel weights creating mass-contamination of soil/water are total BS.

Since brass is composed primarily of copper & zinc, there are certain things that can have great detrimental affects such as ammonia salts that destroy the copper and acids that destroy the zinc. If you dig an old brass cartridge from the ground, often times you'll find it looking powdery and white with small specs of copper showing. This is where the environmental conditions have leached the zinc out of the alloy and thus causing zinc contamination of the soil and ground water because unlike lead, zinc oxide is highly soluble and highly toxic to living organisms.

The amount of lesser alloying elements within the brass will also have an effect on the creation and durability of resultant protective oxide layer depending on the environmental conditions. The same results can be created artificially using a variety of things depending upon the exavt alloy you're dealing with but obtaining a solid even thickness and colored coating is not so easy. When I blacken/tarnish brass like in the pic below, I use my own solution so as to have control over the amount and color of oxides I want to form. In this example, the nominal surface was wiped clean after it achieved the color tone I wanted but the solution was allowed to remain in the engraved cuts to let them darken more for contrast. The desired look on this one is fitting of the historical nature of this style where decoration was almost always done after-purchase and thus maintaining the correct physical aspect of the work as well as the "natural aging" of the metal that of course was done artificially.



Carry the battle to them. Don't let them bring it to you. Put them on the defensive and don't ever apologize for anything."
Harry S. Truman
mark@fire-iron.biz



Edited by - Wolfgang on Nov 08 2009 06:43:13
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