4. Introduction
Metals of one sort or other have been used for at least 14,000 years. The
history of hardened steel goes back three thousand years in the Middle
East. In Ancient times mankind knew only seven metals. These were gold,
silver, copper, tin, lead, mercury and iron. Each was associated with a
heavenly body: gold with the sun, silver with the moon, iron with the Mars,
mercury with Mercury, lead with Saturn, tin with Jupiter, and copper with
Venus. Later zinc and antimony were recognized, though there weren’t
enough planets to fit them into the heavenly scheme. . . The first metallic
alloying element intentionally used in iron or steel was nickel, discovered at
the end of the 18th Century.
The terms used to describe metals, and their heat treatment, are ancient,
and come from that time when there were just seven of them. Our modern
usage of terms such as iron, steel, brass, anneal, etc. rarely means the same
thing as it did in the 18th or early 19th century.
4
5. Wrought Iron, Steel, and Cast Iron
Wrought Iron
“Wrought iron cannot be cast, and cast iron cannot be wrought” was the
ancient view of these metals.
Pure iron is an element, with the chemical symbol Fe, from the Latin word
for iron, ferrum. It is magnetic, and not very strong. Iron has little
commercial value in its chemically pure form, and is usually seen mixed
with, or alloyed with, some other elements. The nearest thing to pure iron
one might commonly find in the hardware store is “black iron wire”,
typically 1008 steel. That is, mostly iron with 0.08% carbon by weight.
The first iron used was meteoric iron, which contains a few per cent of
nickel. Tutankhamen had one dagger forged of meteoric iron, and another
of gold. At the time the two metals may have been comparable in value.
The oldest form in which iron was refined from ore is called “wrought
iron”. This term means just what it says, that it is iron which has been
wrought, or forged, into shape—it is not cast iron. Wrought iron is fairly
pure metallic iron mixed with maybe 3 percent by weight of slag fibres. This
slag is a glass made of iron oxides, and calcium silicates. It runs through the
iron as long stringers. It is lighter than iron, so that 3% by weight means
more than that by volume. If you look at an old piece of rusted wrought iron
you will see a “grain”, or long lines, on the surface. Those long, stringy
marks are from the slag fibres, which did not rust.
Old wrought iron bar found around the Great Lakes
This slag has a positive effect on the properties of wrought iron. One is that
when wrought iron is brought to a forging heat, glowing white hot, some of
the slag melts on the surface and acts as a flux. This permits two pieces of
wrought iron to be readily forge welded together. Herodotus says the art of
welding was discovered by Glaucus of Chios. Indeed, for nearly three
thousand years forge welding was the only kind of welding.
5
6. Then about a century ago a process was developed to “weld” steel by
melting an iron wire into the joint. Since that time the word “weld” has
meant a process of joining two pieces of metal by melting the edges, as well
as melting a metal wire (the “weld rod”) into the joint. However, all welding
used in the production of a muzzle-loader was done by forge-welding.
Since modern steel, by whatever name, lacks this slag, the modern
blacksmith may sprinkle a flux on his hot iron to aid in forge welding.
The presence of these slag fibres also gives wrought iron a grain, rather like
wood. That is, across the grain it is more likely to break, just like a wooden
board. When wrought iron is forged into a part, like a Colt revolver frame,
care is taken that the “grain” runs in the way that the part will have the
most strength. If you closely examine firearms of the Civil War and earlier
you may sometimes marks, or seams, from these slag fibres. They show in
Spencer rifle frames, which were wrought iron, and sometimes in Colt
revolver frames, made of Norwegian wrought iron. Confederate revolvers
sometimes used wrought iron, instead of steel, for cylinders. They twisted
that iron to increase the bursting strength of the cylinder. The spiral lines
on many Confederate revolver cylinders are from slag in the wrought iron.
slag
Colt Navy Brevete
6
7. The marks on the case-hardened frame of this Navy Colt Brevete are from
slag in the wrought iron. The frame forging was in an “L” shape, and the
slag lines roughly follow around the corner of the “L”.
close-up of frame
Marks like this on an old gun indicate
either that it is an antique made of
wrought iron, or that it is a very well-
thought out fake. I once saw such slag
marks on an “antique” tomahawk, then
later realized it was an investment casting,
with “slag lines” cast right into it.
The last American made wrought iron was
puddled in 1961. It is wonderful stuff for
the blacksmith but unfortunately must
now be located piece by piece, from
antique scrap.
The master, right, taps the place where his
helper is to strike a heavy blow, with both
hands. Farrier’s tools haven’t changed in five
centuries.
Der Schmidt, Jost Amman 1500’s
7
8. For centuries gun barrels were made by forge-welding a skelp of wrought
iron into a tube, boring, reaming and straightening. The process for rifles
is well described by Captain John G. W. Dillin1, The Kentucky Rifle, and by
Walter Cline2. Great detail of musket barrel manufacture is given by Merritt
Roe Smith3.
While the slag makes wrought iron relatively easy to forge weld, hand-
forged welds are not terribly reliable. The failure rate in proof of hand
forged barrels at Harpers Ferry arsenal was in excess of 25%, and
sometimes exceeded 40%. At Springfield Armory water-powered trip
hammers provided a heavier, more consistent blow to effect the weld.
Barrel loss in proof at Springfield was down around 8-12%3.
I understand that the older generation of muzzle-loading shooters, in the
1930’s, preferred wrought iron barrels. When I was younger, and still
immortal, I used to shoot 19th century wrought iron pieces. After perhaps
twenty years as a metallurgist I got around to looking at (what passed for)
welds in wrought iron barrels. With all respect, you can have them. Mine
will stay on the wall. Unfortunately that is not to say that some modern
muzzle-loading barrels are any better, due to poor choice of steel. One
common choice, AISI 12L14, has very low ductility, about 8% across the
grain, with low impact properties4. This steel has good tensile strength, but
does not well tolerate seams or other flaws. Now & again this costs someone
a hand.
Steel
Steel is, for the most part, iron with some the addition of up to 2% carbon.
Carbon, that black element we most commonly see as soot or lamp black.
Reasonably pure iron, such as wrought iron, cannot be hardened at all by
heat treatment. It is the presence of carbon that permits this metal to be
hardened by heating red hot and quenching in water or oil. Hardened steel
is used for springs, knives, axes, swords and other tools.
Names have different meaning today than in older times. The metal
commonly called "steel" today, like steel nails, I-beams and auto sheet
metal does not have enough carbon to harden, and did not exist in olden
times.
Let us start with steels used for swords and daggers. Three types are the
Oriental, or authentic, Damascus steel; layer welded steel; and pattern
welded steel. That last one is commonly referred to as "Damascus" steel,
when it is used for shotgun barrels of the 17th through early 20th centuries.
8
9. To digress, the first steel tools were most
likely forged from iron meteorites. I
believe the words for “steel” in various
languages have the same root as the word
“star” in those languages, as steel came
from the stars. The Egyptian King
Tutankhamen was buried in 1352 B.C. with
two daggers of precious metal, one being
gold, the other iron. The value of those two
metals may have been comparable, at that
time.
His 13-3/16” dagger was made of iron with
about 3% nickel in it. The nickel content
means that it is most likely of meteoric
origin. The sheath is of gold.
from www.eternalegypt.org
Oriental/Authentic Damascus, Layered Steel, and Pattern
Welded Steel5
Authentic, or Oriental, Damascus
Is also called "wootz", the Indian word for "ingot". Over perhaps two
thousand years this steel with the "watered pattern" has become the stuff of
legend. It was made by melting wrought iron in a clay crucible, with
charcoal or leaves added to get the carbon content up very high, 1-1/2 to 2%
carbon by weight. Until the land trade routes were closed by the Arabs even
the Vikings made some swords of this steel. It became known in Europe as
Damascus steel. There are different opinions regarding the origin of this
name. One is that fine swords and knives were made out of wootz in the
Islamic world, and Damascus was an important trade center on the route
between India and Europe. The steel blade below shows the pattern known
as Mohammed's Ladder, or Kirk-Narduban, produced by a special forging
technique.
9
10. To bring out the pattern the steel blade is polished, then etched with mild
acid to bring out the pattern in the steel itself. Acid darkens the steel, but
leaves the coarse iron carbides lighter. Different forging techniques can
make elaborate patterns, including one known as Mohammed's Ladder.
Production stopped in the mid-nineteenth century for various reasons. One
may have been depletion of the iron ore deposits in Hyderabad, India.
Layered Steel
This Indonesian Kris is made of "layer-welded steel". Layers of different
types of steel, both low and high carbon, were forge welded together. The
forging was cut in two pieces, piled up and forge welded again, sometimes
several times. After the blade had been forged to shape and polished,
etching showed the pattern where the different grades of steel met. Some of
the iron or steel involved may have contained a little nickel, which will be
less affected by the acid. Today the etching is still done, in Indonesia at
least, with a piece of citrus fruit and a bar of "warangan" , an Asian name
for a mineral high in arsenic trioxide (As2O3).
Pattern Welded Steel
This is what we see in old "Damascus" barrel shotguns, such as this 8 gauge
Tryon used for market hunting on the Chesapeake Bay. Barrels were made
by twisting together rods of low carbon wrought iron and high carbon steel,
then forge welding them to combine the ductility of soft iron with the
strength of steel.
10
11. Steel—Blister Steel (cementation steel) and Cast Steel
Blister Steel
Because wrought iron has very little carbon, it will not harden when heated
cherry red and quenched in water. Wrought iron makes good horseshoes
and gun barrels but it is useless for knives, swords, axes and other cutting
tools. It must have a decent amount of carbon in order to harden.
Steel, in the old terminology, is the element iron with a certain amount of
carbon in it, typically from about 1/5th of a percent up to maybe 2%. It is the
carbon that permits steel to become hard when it is heat treated. There
have been a number of ways to make steel through the ages, but for the
most part only two were used for the antique guns in your collection.
The first process was “cementation”. Long flat bars, or “skelps”, of wrought
iron were packed in a large box, with charcoal all about them. The box was
closed up, sealed with fireclay and heated bright red hot for about a day. At
this high temperature carbon from the charcoal gradually “soaked” into, or
diffused into, the iron. This kind of process was, and still is, referred to as
cementation.
When the steel maker thought it should be about finished he would
withdraw a test bar and quench it in water. Then he broke it, to see the
“depth of steeling”. If the bar had absorbed carbon all the way through, it
would become very hard all the way through from quenching. When
broken, the fracture would be bright and crystalline in appearance.
If the process was not quite finished there would be a soft, low carbon
center to the bar. When broken, that part would appear fibrous, and
different than the hard steel “case”.
As carbon diffused into the bar it reacted with the iron oxide in the slag.
Carbon reduced these oxides to metallic iron. The process gave off carbon
monoxide gas. That gas raised blisters on the bar surface, hence the product
was known as “blister steel”. It was the lowest grade of steel made. The
carbon content was highest on the surface, and lowest in the center. In
order to use blister steel at all, one needed to at least forge the blisters shut.
The next better grade was “shear steel”. Blister steel bars were sheared in
half, bundled together and forged to make “shear steel”. Forging the bundle
down to a new skelp made the high and low carbon layers thinner. But, the
metal still was not of uniform chemistry, and it included the same slag
stringers that were in the original wrought iron skelp.
11
12. The Democratic Expounder, Marshall, Calhoun Co., Michigan, February 21, 1851
The frizzen spring of this Italian snaphaunce has a long seam, caused by the
ever-present slag in the steel of that time. It is not the fault of the locksmith,
nor is it a crack caused by long usage. It was there from the beginning. It
might not have been noticed until time, and some corrosion, accentuated it.
A flintlock frizzen is forged of soft wrought iron. In order for it to spark, the
surface must somehow be hardened. Frizzens (hammers, more correctly) of
flintlocks were “steeled” by forge welding or brazing a piece of steel onto a
wrought iron part. When that steel wore out it could be replaced by another
piece, brazed on.
12
13. I examined two original American flintlock rifles and a Ryan & Watson
brass barreled pistol, all three with a flat piece of steel brazed to the iron
hammer. On the Ryan & Watson the steel is about 40/1000” (1 mm) thick.
Military arms and better English pistols show no braze line, so it seems
reasonable to assume the steel was forge-welded to the wrought iron back.
The whole thing might have been lightly case hardened when finished.
It would have been very impractical, in my opinion, to case carburize an
entire wrought iron frizzen deeply enough to be useful. On wrought iron,
deep carburizing generates carbon monoxide, which raises blisters. This
distorts the metal & requires forging to weld these blisters shut.
American flintlock rifle, late style, with a piece of steel nearly 1/16” (1.5mm) thick
brazed onto the frizzen. The rifle itself shows very little signs of use, so this might
have been done when the lock was made. Capt. John G.W. Dillin illustrates this
same rifle, from the Clarence St John collection, as No. 3, Plates 93 & 94.
13
14. Cast Steel Acier Fondu
The first thing any gun collector should know about cast steel is that “CAST
STEEL” stamped on a gun barrel absolutely does not mean that it is a
casting. It was the 18th & 19th Century way of describing a metal that we
would just call “mild steel, carbon steel, or high carbon steel”.
In the early 18th Century a watchmaker named Huntsman in Sheffield,
England was dissatisfied with the shear steel available for mainsprings. It
was not uniform in properties, so that the mainspring delivered erratic
power to the gear train. In turn, the watch was not so accurate.
With knowledge gained from potters in the area, Mr. Huntsman developed
a process to make steel of uniform quality, that is, having the same carbon
content throughout. What he did, in 1744, was to place short pieces of
blister steel in a crucible. He then used advanced furnace technology from
the potters to heat that crucible hot enough to actually melt the steel. That
required heating the metal to around 2700—3000°F. It was the first time in
the Western world than anyone had ever melted steel.
Once pieces of blister steel melted, the carbon mixed uniformly throughout,
and molten slag floated to the surface. Huntsman poured his crucible full of
molten metal into a mold—he “cast” it—to make an ingot. Then the ingot
was reheated, and forged down into a bar of desired size or shape.
Because the steel was actually melted and poured into a mold, it was called
“cast steel”, to distinguish it from blister steel. Melting steel and pouring it
into an ingot was quite an advance in technology for Europeans.
Of course, our Indian associates would remind us that the famed Wootz
steel, or true Damascus steel, had been produced by the crucible process in
India for perhaps 20005 years. Wootz was a very high carbon steel, not
uncommonly about 1.7% carbon. 18th century Englishmen paid high prices
for a razor forged of Indian "Damascus" steel.
14
15. English cast steel of the 18th century was iron with about 1% of carbon in it.
Various carbon contents, which they called “tempers”, were available. This
steel was used for knives, swords, axes—in short, all manner of cutting
tools. Circular saws in the 1866 city directory for Detroit were advertised as
“Cast Steel Saws”, or “WM. JESSOP & SON’S ENGLISH CAST STEEL
SAWS”.
High carbon steel like this is strong, but it is not ductile enough for a gun
barrel. As time went on, the English learned how to make a lower carbon
cast steel, a “decarbonized steel”. This metal, very roughly similar to a
modern AISI 1040 or 1060 steel, could be used to make gun barrels.
In the US this lower carbon cast steel was first used in pistols. Steel barrels
were used by Allen in his Pocket Rifle (underhammer pistol) by 18376. All of
the Allen & Thurber pistols I have seen have been marked “CAST STEEL”.
Samuel Colt used steel for the cylinders and barrels of his revolvers.
Originally he may have used American steel, but by about 1850 he was
getting steel from Thomas Firth, of Sheffield, England7. Eventually “cast
steel” rifle barrels came into more common use, either bored from solid or
rolled out from a pierced billet to have a rough hole already in them. Ned
Roberts8 describes these and opines that those bored from solid shot better.
The major 19th Century supplier of barrel blanks to the gun trade was
Remington. Quite a number of rifles may be found stamped REMINGTON
on one or other of the flats near the breech. Remington supplied barrels,
locks, and mountings, only. To my knowledge they did not make complete
percussion rifles, their name simply indicating the source of the barrel.
Breech end of barrel on a W. Robinson rifle, stamped REMINGTON
Remington supplied barrels to the trade at least as early as 1825. Possibly at
this early date they may have been wrought iron, and not steel, barrels. The
account book of Alvin D. Cushing, gunsmith of Troy, New York, has
survived and is in the Historical Society, Troy, New York. Courtesy the late
H. Jerry Swinney, I saw that this book had notations for October, 1825
which read: to 7 rifle barrels Remington $21 1 burst barrel
$1.50 1 burst barrel $1.50 14 rifle barrels $42.
15
16. Four different stamps have been observed on Remington barrels9
P & S REMINGTON REMINGTON REMINGTON
CAST STEEL
The earliest, according to S. James Gooding, is the semicircular form,
found on Canadian rifles circa 1834-1841. P & S REMINGTON was found on
two Canadian rifles from about the 1840’s through the 1850’s. Marcot10
notes that P & S REMINGTON stands for Philo & Samuel Remington, who
were in business about two years, beginning about 1843. REMINGTON was
found on a Canadian rifle dated 1840—1850, on a William Robinson rifle
made in Mt. Clemens, Michigan some time after 1857, and on a rifle by H. F.
Palmer, active in Michigan approximately 1862—1878. REMINGTON over
CAST STEEL may be slightly later.
Other contemporary sources for rifle barrels include a barrel forge in
Mott’s Corners, southeast of Ithaca, New York. This may be the same forge
which H. Jerry Swinney noted was operated by Lull & Losey, northeast of
Ithaca. Another company, Hitchcock & Muzzy, later Muzzy & Co., of
Worcester, Massachusetts, also supplied steel barrels to the trade.
This barrel is on a half-stock target rifle by C.L. Cone, HITCHCOCK & MUZZY
made somewhere in New England. It came to me from CAST – STEEL
Vermont.
Through the first part of the 20th Century tool steels were melted in small
crucibles, and the product was known as “crucible steel”. Around 1850—
1860 Whitworth’s Fluid Compressed Steel became available in England, as
well as Bessemer steel. When I examined the microstructure of a Fluid
Compressed Steel rifle barrel, it appeared to have about 0.35% or so
carbon, and was annealed.
16
17. In all cases the steel barrel was much stronger than wrought iron, and did
not contain the weak zone caused by the weld.
However, any steel may contain defects, and even modern steel rifle barrels
must be magnetically inspected for seams, then proof tested in addition.
Few contemporary manufacturers of muzzle-loading rifle barrels bother
with such niceties. Such barrels may be comparable to, at best, mid-19th
Century standards of safety and reliability.
Until just after our Civil War the best Cast Steel came from Sheffield,
England. Not only did the English have skilled & experienced workmen,
they also had long term contracts for the best grades of Swedish charcoal-
smelted finery iron made. American importers got Swedish iron considered
“second mark” or “common” in Sheffield. In addition the clay used in
Sheffield for crucibles, Stourbridge clay, had superior properties for
deoxidizing the molten steel at the final stage before pouring into the ingot
mould. American cast steel of consistent quality was not made until the
1860’s. It was developed to serve the Collins Axe Company, who disliked the
erratic response to heat treatment of American made steel at that time.
Cast Iron—Gray and Malleable
Gray Iron
Gray cast iron is the traditional brittle cast iron of which frying pans, old
iron stoves, engine blocks and cannon shot were cast. It is called gray iron
because when it is broken the fracture surface is gray in color, from all the
graphite flakes in the metal. Gray iron has no ductility when loaded in
tension, nor can it be bent. Muzzle-loading cannon of gray cast iron were
used, but did eventually blow up. Gray iron was ideal for explosive shells.
Fragment of a
cast iron 11 inch
shell, delivered
to Fort Fisher,
North Carolina,
C.S.A., January
15, 1865 by the
Federal fleet
under Captain
Kidder
Randolph
Breese.
17
18. Malleable Iron
This is a form of cast iron which has some degree of ductility. It was
commonly used for pepperbox frames, nose caps of US muskets and other
parts where resistance to repeated shock was not required.
During the Civil War when demand for revolvers was high, Remington
began making revolver frames of cast malleable iron, rather than forged
wrought iron. The military11 asked Remington to go back to wrought iron.
It is not clear that they did so. One such malleable iron revolver, later
converted to cartridge for the U.S. Navy, is shown below.
Malleable cast iron was developed in the early 18th Century by a French
man, de Réaumur12. He was looking for a process to make decorative iron
fences and gates without the labor intensive process of hand forging each
piece. They could be cast of gray iron, of course, but the result would be too
brittle to handle well without breakage.
Now, if gray iron is made with insufficient carbon, or freezes quickly in the
mold, it becomes extremely hard, too hard even to grind, and brittle. When
broken the fracture is bright and shiny, which is why this type of cast iron is
called “white iron”. Réaumur found that annealing this white iron for a day
at red heat, 1750°F, eliminated the brittleness, and gave the metal some
amount of ductility.
Thick sections in castings may have shrinkage voids form during solidification.
This Remington Navy had the recoil shield machined away in the process of
converting it to cartridge. Shrinkage in the casting is now revealed, about in the
center of where the recoil shield had been.
18
19. When Colt established his London operation he decided to make the trigger
guards of iron, rather than brass, to suit the British preference. Like the
brass guards used in America, the English trigger guards were cast. In
Colonel Colt London, Joseph Rosa states that “At first, the guards were so
brittle that they snapped like glass when they were taken from the moulds.
But it was later reported that “after having undergone the annealing, they
became so tough that they will bear hammering out, or may be bent into
any irregular shape. . .” This is descriptive of malleable iron. When cast it
is white iron, which is exceedingly brittle. After annealing for a day it
becomes “ferritic malleable” and has some reasonable ductility.
Copper alloys—Bronze, Brass and German Silver
Bronze
The first copper alloy used in history was arsenic bronze, followed by tin
bronze about 5000 B.C. in the far East. The weapons Homer speaks of in
the Iliad were all of tin bronze. Roughly speaking, you may consider bronze
to be an alloy of copper and tin, while brass is an alloy of copper and zinc,
and German silver is a mixture of copper, zinc and nickel. The SAE in 2004
listed over 500 different alloys, whose names include various combinations
of the words copper, brass and bronze. The alloying elements used now
cover the alphabet from the most ancient, Arsenic, to the newest,
Zirconium.
You might find it useful to remember the differences amongst tin bronze
and brass, copper and gilding metal. They are all different shades of red and
yellow. Nickel silver is nearly white. This name is often confused with a
similar alloy called German silver, which has a slight yellowish cast to it.
Bells are made of bronze with about 22% tin
and 78% copper. This makes a fairly hard alloy
with a good ring. This hard metal may also
crack if the bell is hung wrong. You may recall a
famous bell cast in Philadelphia which cracked
when rung quite vigorously. If one is to melt
down church bells to cast cannon, one must add
some copper to the melt so the metal is ductile
enough for a gun.
“Because of its particularly sonorous quality,
bell metal, containing from 20% to 24% tin, is
used for casting bells.”
Church bell of Sienna, A.D. 1159
hwww.msu.edu/~carillon/batmbook/chapter4.htm
19
20. This 12-pound Napoleon, at Rock Island Arsenal, was cast of a 90% copper,
10% tin alloy13. The weathered surface has pattern, from the large cast
grains and the fine, needle-like structure of a tin-rich phase. More tin would
increase tensile strength, but at the expense of toughness.
One can sometimes tell the difference between a weathered piece of tin
bronze, and a like piece of brass, or brass with a little tin, by appearance.
Brass castings do not have the fine pattern caused by tin, all one can see is
the individual grains. You may see this on brass door handles outside public
buildings, which have been polished and etched by years of handling.
Many alloys, called variously brass or bronze, are alloys of copper with both
tin and lead. One such is cast Gunmetal, also known as Government Bronze
G, with the Unified Numbering System identification C90500. The alloy is
nominally 88% copper, 2% zinc and 10% tin. In practice a little lead may be
added to improve the soundness of the casting, and for machinability.
20
21. Analyses of this Sharps 4-
barreled pistol, .30 rf
model 2-A, and of a Henry
marked model 1866
Winchester, show both
their frames to be cast of
“Gunmetal”.
The Confederate States of America manufactured weapons under some
material constraints. Nevertheless, the one Confederate revolver I was able
to examined indicated a sophisticated degree of metallurgical control. The
lockframe analysis of this Spiller & Burr revolver fell exactly within our
contemporary specification for Valve Bronze (a.k.a. Navy M, or Steam
Bronze). That is, 88% Copper, 6% Tin, 4% Zinc, and 1.5% Lead.
I am told that this Spiller & Burr had been stored in an old horse barn.
Store neither your modern ammunition, nor your powder flasks, either in
the barn, or near the kitty litter!
21
22. The cracks in the frame, shown here, along with several others in the grip
frame, bring up an important point about copper alloys. They are all subject
to “season cracking” in the presence of ammonia or other nitrogen
compounds. A 1942 metallurgy book14 states: It is well known that the
atmosphere in the vicinity of stables and farm yards is a very dangerous
one for stressed brass, and in olden times a car garaged in farm buildings
often exhibited many season-cracked brass parts. It is not such common
knowledge that the urine of rodents and of some other animals—for
example, cats—quickly produces season-cracking, and that many tons of
cold-drawn brass have been ruined annually owing to the unwelcome
attention of mice and rats in old warehouses. . .”
In the copper-tin-zinc series of alloys tin adds to strength, and perhaps to
castability. From the 1840’s through at least the 1860’s, American brass gun
mountings often were cast of an alloy with 2 or 3% tin and 15—18% zinc.
During my testing I found this to be true of an Aston model 1840 “horse
pistol” dated 1847, and several Colt revolvers dating from about 1848
through 1862. The guard of one Model 1860 Army, made in 1862, was cast
of 78% copper 18% zinc 3% tin, with just under 1% lead. Later tensile testing
showed that zinc was approximately twice as useful as tin for increasing
strength, and this class of tin-bearing alloy went out of use.
The U.S. attempt at a metal “gold” dollar used a
sort of copper-zinc-manganese-nickel bronze.
George Washington has his portrait on this one,
of metal which is about 78% copper, 12% zinc
with 5% each of manganese and nickel.
Brass
Brass is normally thought of as copper with zinc added. Modern cartridge
brass is 70% copper 30% zinc. Copper-zinc alloys range from 5 to 40% zinc.
Early metallic cartridges were of what today is called “gilding metal”, an
alloy of copper with just 5% zinc. The zinc improved both strength and
ductility, so the metal better withstood drawing into a cartridge case.
22
23. Below is a .45-70 “Multi-Ball” cartridge, designed to more effectively
destroy the last free people in North America. The case is 94.8% copper
5.2% zinc, known at that time as Bloomfield’s Gilding Metal15. This 5% zinc
alloy is stronger than pure copper, but not as strong as the 70% copper 30%
zinc cartridge brass used today. Gilding metal is now used for bullet jackets
(metal patched bullets, to use an older terminology)
A Batty “Peace Flask” dated 1848 has a body of similar composition. It is
94% copper 5.3% zinc, with residual amounts of lead, 0.4% and nickel,
0.3%. The spout is more or less conventional brass, 76% copper 23% zinc,
with residual amounts of lead, nickel and iron. In both parts lead might
have been added intentionally, nickel and iron just came along with the
copper ore at that time.
The brass patchbox lid & head, buttplate and trigger guard of this Harpers
Ferry rifle dated 1818 all fall into the chemistry range of 64-76% copper, 20-
34% zinc with 1.3-2.5% lead.
Lead in these and other brass parts is the reason one must not heat brass to
bend it. The lead melts, or comes close to melting, and with a little bending
it runs along the grain boundaries so that the part breaks, or crumbles, in
two. Bend all brass, new or old, at room temperature
Pinchbeck alloy is a brass made with relatively low zinc content. Various
references state anything from 7% to 19%. It resembles 20k gold in
appearance, and was often used as a cheap substitute. It was invented by
Christopher Pinchbeck, c1670 - 1732. Pinchbeck was a London maker of
clocks, jewelry and musical automata. Whereas Pinchbeck himself clearly
labeled his jewelry, later dishonest jewelers passed off pinchbeck alloy as
genuine gold. In the 19th century pinchbeck" became a metaphor for
spurious or counterfeit.
23
24. The grips of miniature pocket pistols such as this one, about 1-3/4" long,
were sometimes made of alloy generally called Pinchbeck. Pieces that date
after about 1840 are rarely of true pinchbeck.
Pinchbeck became supplanted by 9K
gold, legalized in 1854, and newer
gilding techniques.
German Silver, Nickel Silver
The most commonly available “German” silver alloy available today is
called, variously, Nickel silver 65-18, or 18%—alloy A. The UNS number for
this grade is C75200. Nominal chemistry is 65% copper, 18% nickel and 18%
zinc. It has a silver-white color. The whiteness in nickel silver comes mostly
from the nickel content, and to a lesser degree from zinc. I have observed
that the alloy used on old American rifles has a more yellowish cast than
seen with modern alloy.
White colored copper-nickel alloys had been used in Europe and China for
centuries. Our metal called German Silver was developed by Berndorf AG in
1823, and tradenamed "Alpacca".
There are many “nickel silver” alloys listed today. One current alloy which
is actually tradenamed German silver, rather than Nickel silver, is 65%
copper 12% nickel and 23% zinc. UNS C75700. Because of lower nickel, this
grade may be expected to be somewhat less white in color than the 65-18
alloy. By comparison it appears yellowish. This matters when one attempts
to repair an inlay on an old rifle, and exact color match becomes important.
The German silver trim on the sheath of this old Bowie knife, marked
NON•XLL Joseph Allen & Sons, Sheffield is 61% copper 24% zinc 14% nickel,
with assorted residuals. This metal has a yellowish cast, which is not
matched by the new sheet of nickel silver in my shop.
24
25. Pewter was an alloy of tin, lead, and copper, occasionally with antimony.
Britannia metal, 93% tin 5% antimony and 2% copper is used today, instead
of the old lead-bearing pewter alloys. To get the gray or dark gray
appearance of an old cast pewter nose-cap on a percussion rifle, use one of
the old alloys of tin, lead and copper, or for convenience just tin and lead.
My uncle sent me this antique pewter
mug from England after WWII. I used
to drink milk out of it as a child.
Some would frown on this practice now.
The bottom is pitted from corrosion, and
there are whitish corrosion products around
the inside surface.
Recent chemical analysis showed this old
English pewter to be 95.7% tin, with 1.6%
of lead, 1.7% antimony, 0.7% copper, and
a little arsenic, 0.2%, for good measure.
Made me what I am today.
This very old plate is closer
to what I think of as pewter.
It is 82.5% tin, 16.5% lead
and 0.9% copper.
Not a good idea to eat
tomatoes off of such
a plate.
25
26. Tin
Usually when one says "tin" one means tin plated iron, such as a modern tin
can or antique lantern, candle mold, &c. This unpleasant relic of our 19th
Century Indian policy was on display at a local show. It is a solid tin alloy.
The tin is alloyed with a little antimony and copper for strength. Analysis is:
91-1/2% tin, 5-1/2% antimony, 1-1/2% lead, 1% copper and 1/2%silicon
Whoever No 48 may have been, US policy was that his body belonged to the
US Gov't and not to his surviving relatives or tribe. This is our history.
"It is, to be sure, a hard thing to say, but there is safety in extermination
alone, and this can be effected only during the early spring, when the
Indians are in their villages." A Stage Ride to Colorado, Harper's New
Monthly Magazine, No. CCVI - July, 1867 - Vol. XXXV
Silver available in jewelry supply stores is sterling silver, 92.5% silver 7.5%
copper. Coin silver was typically 90% silver 10% copper. The copper
addition made it a bit harder, to better survive circulation. Coin silver has a
slightly different color than does pure silver. Old silver may have a few
tenths of a % lead in it, a residual from the refining process formerly used.
Silver plating on old firearms has a tin addition, in the range about 3 to 6%.
When coin or sterling silver is annealed in air, the copper oxidizes faster
than does the silver. After the black copper oxide scale has been removed by
pickling the copper is depleted, and the surface enriched in silver.
4 Reales coin from the 1540’s, Mexico mint, Juan Gutierrez assayer. The
fineness of the bullion was set at 93.051% silver16. Because the copper-
depleted surface has not been worn away from this coin, the surface is
enriched to 98.9% silver rather than the specified 93% silver. There was
only 0.7% copper.
26
27. Refining operations at that time
involved lead, and there is a
residual 0.3% lead in this coin.
What I find interesting is that it also
has 0.1% tungsten, from the original
Mexican silver ore.
Nominal Chemical Analysis of Copper Alloys
Common UNS Copper Tin Zinc Lead Nickel
Name number17
Nickel Silver C75200 65 -- 17 -- 18
German Silver C75700 65 -- 23 -- 12
Cartridge Brass C26000 70 -- 30 -- --
Free Cutting Brass C36000 62 - - 35 3 - -
Bell Metal (cast tin bronze) C91300 80 19 -- -- (0.5P)
Red Brass C23030 85 -- 15 -- --
Valve Bronze C92200 88 6 4 1 --
Gunmetal C90500 88 10 2 --
Leaded Com'l Bronze C31600 89 -- 8 2 1
Commercial Bronze, 90% C22000 90 - 10 --
Phosphor Bronze C52480 90 10 -- -- --
Gilding Metal C21000 95 -- 5 -- --
Ampco 45 C63000 82 - - - - - - 5
Ampco 45 also contains: 10% aluminum, and 3% iron
UNS stands for Unified Numbering System designation, meant to render all old trade
names and Copper Development Association numbers obsolete. Nevertheless, if you buy
cartridge brass the supplier will call it C260, not C260, &c.
UNS numbers are used in the U.S.A. only. Europeans use EN, European Normal, which
standards appear to be largely adapted from the German Industry Standard (DIN).
Chemical Analyses: All copper, silver and lead alloy analyses in this paper
were performed by an Innov-X Systems Model #XT-245S spectrometer.
This X-ray fluoroscope leaves absolutely no mark on the metal.
27
28. Nominal Carbon Content, Modern Carbon Steels
AISI Carbon Common Applications
1018 0.18 “Mild Steel” can be case-hardened
1035 0.35 Shafts, Gears
1060 0.60 Sledge hammers
1070 0.70 Springs
1095 0.95 Star drills, Cement Chisels, Springs
US and English measures
multiply by to get
ell 45 inch
rod 16.5 f00t
league 3 mile
pound 7000 grain
cwt (hundredweight) 112 pound
Old French measures
pouce 12 ligne
pied 12 pouce
pied 1.066 feet
arpent 180 pied
arpent 192.24 feet (US Standard)
livre 0.9266 pound (US Standard)
Most of these are from: www.convert-me.com
Old Chemical Names
Aqua Fortis nitric acid, HNO3
Black Brimstone crude sulphur
Black Lead, Plumbago graphite
Blue Vitriol, Blue copper sulphate CuSO4•5H2O
Copperas
Butter of Antimony amtimony trichloride SbCl3
Brimstone Sulphur, S
Copperas originally blue vitriols, Later sometimes used for
all vitriols/sulphates
blue copperas copper sulphate, CuSO4
green copperas ferrous sulphate FeSO4•7H2O
28
29. Old Chemical Names, continued
Corrosive Sublimate mercuric chloride HgCl2
Crystallised Vertigris cupric acetate, Cu(C2H3O2)2•H2O
Cyprial Vitriol copper sulphate CuSO4
Dragon’s Blood the resinous fruit of Daemonoraps; also resin
from the fruit of a Malayan rattan palm Calamus
Draco, other species of Calamus, or the tropical
American tree Lingoum Draco, or the blood tree
Croton Draco
Minium red lead, Pb3O4 (formerly referred to cinnabar,
mercuric sulphide, HgS)
Muriate of Iron iron chloride
Spirits of Wine ethyl alcohol C2H5OH
Sweet Spirits of Nitre 4% solution of ethyl nitrate, C2H5NO3 in alcohol
Shell lac orange shellac
Spirit of Hartshorn ammonia, NH3
Sugar of Lead lead acetate, Pb(CH3CO)2•3H2O
(saccharum saturni)
Tincture of Steel, of Iron alcoholic solution of ferric chloride FeCl3•6H2O
Gum Sandarac resin from the Sandarac, or avar, tree, Morocco.
Vitriolic acid, sulphuric acid, H2SO4
Oil of Vitriol
Sources for chemical names include:
Browning of Firearms (Part Two—Conclusion), C. Meade Patterson, The
Gun Report, February 1962
The Condensed Chemical Dictionary, Fourth Edition, Reinhold Publishing
Corp, 1950 NY
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