VII. Reloading Information
B. Bullet & Shot Information
5. A Few Notes Regarding Cast Bullet Alloys
by Norm Johnson (njohnson@nosc.mil)
There are a great number of old wives tales regarding lead alloys
as pertain to bullet moulding and how to achieve practical
accuracy with those bullets. Let us use the inquirie answering
technique.
> I do not understand why a lead cast bullet can only contain a few
> percent (2 to 3) parts of tin to be classed as hard.If an alloy
> of 70% lead and 30% tin was used it will still be "softer" than
> copper. What gives?
Historically, bullet lead is hardened, principally, by addition
of antimony and minute mounts of arsenic. Lead will harden
slightly with 2-3% of tin added but more than this will not make
much difference, at least not enough difference to justify using
expensive tin to do it. Tin is added to lead in small amounts
because it will enable better mould fill-out than will pure lead,
and not to (appreciably) harden the alloy. More than 2-3% tin is
a waste of money. Many old wives tales abound about bullet
casting alloys; these can be destructive of bullet caster's
efforts if they are believed.
> I have come into possession of about 100# of melted down and
> cleaned up wheel weights, six lead bricks of unknown composition
> (soft) and 5 -10 # of Linotype. Is there any method besides
> trial and error of turning this mess into good bullet metal?
BEWARE -- BEWARE - BEWARE
Before you mix any quantity of the unknown metals that you men-
tion, be aware that even minute amounts of aluminum or zinc can
completely ruin the casting properties of the metal. Before you
mix those different lots of metal, take a sample of each, add
enough solder to provide 2% - 3% of tin to the mix, and cast. If
the unwanted metals are present you will positively NOT get
filled out bullets (although there are other factors can cause
the same problems).
Casting pure Linotype is very satisfying because it makes such
beautiful bullets. It is not done much because of its expense
and is most often used as a source of tin and antimony. Wheel
weights alone or with the addition of 2 to 3 percent tin is
excellent bullet metal and has the added advantage of being about
the right hardness (strength) to make good hunting bullets;
Linotype shatters and SHOULD NOT be used for big game hunting.
Recycling bullet metal is common and any tin burned off in the
process can be easily replaced by the addition of a little sold-
er.
The Cast Bullet Association has a great wealth of articles on
alloys. Please be aware that a good deal of bad casting/alloy
information has been printed in the popular gun rags in the past
and continues to be. The Cast Bullet Association has been
blessed with having members that are professionals in various
fields and those members (like Dennis Marshall) have put to rest
a good deal of misinformation that writers have spread over the
years. There is so much to be learned (or corrected) that lots
of reading is necessary.
The single, most comprehensive yet concise article that I have
seen on bullet metals was published in the 1991 Fouling Shot,
Jan-Feb issue, beginning on page 89-8.
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The only control one has over the as-cast bullet diameter, using
a given mould, is to vary alloy types. The higher the antimony
percentage, the larger the bullet diameter. For instance:
Bullet alloy diameter weight (grains)
lead .3578 215
wheelweights .3584 212
Lyman #2 alloy .3590 206
Linotype .3594 200
Sometimes trying a softer bullet - even though it will cast a
slightly smaller diameter bullet, the resulting increased obtura-
tion may fill the throat adequately to reduce gas cutting.
Incidentally, the resulting diameters of these bullets pushed
through a given sizing die will differ also as the high alloy types
have more "spring back". When pushed through a .357" sizing die,
the Linotype bullet will be about .0007" larger than the lead
projectile.
For light target loads or those that use low pressures, lead and
2-3% tin for easy fill-out is usually all that is necessary (or
desirable).
> Someone on some list posted a caution about using modern wheel
> weights for casting but I have lost the info. I remember that
> apparently the new style (shiny) contain Zinc which caused some
> problem or other.
The "modern" wheelweights, if you mean the tape type stick-on,
are not worth the fuss as they will gum up your pot beyond be-
lief! As far as I know, they do not contain zinc, however.
> What problems does Zinc cause? Is there a reasonable way to "flux
> it out"? Could I use them for something else (swaging maybe or
> pouring into a copper jacket to make FMJ...?
Zinc ruins bullet metal in that it prevents mold fill-out. It
cannot be removed by home methods and is to be scrupulously
avoided.
One exception; pure zinc bullets poured in straight sided molds,
where fill-out is not so much a problem, shoot very well and act
like FMJ bullets. They are VERY hard. Use just like jacketed
bullets - no lube. My Dad gave me lots of zinc about 35 years
ago and I had a good time with it.
In that same line, if you have a core mold, zinc contaminated
metal should work well for jacketed bullet cores. I make .22
caliber bullet jackets out of fired .22 LR cases and use dubious
alloy as cores. Corbin makes both the core molds and the dies to
form jackets from .22 LR cases. It is not a complicated proce-
dure and I experimented with it so that, God forbid, jacketed
bullets are someday not available, I will have a source for
my .22 centerfires.
If you choose to try pure zinc bullets, make sure that, when
returning to lead casting, your equipment is thoroughly scrubbed,
as it takes only a slight amount of zinc to contaminate your lead
alloys.
I have been unable to swage pure zinc - even on my old C-H Swag-
O-Matic which swages the hardest lead alloys with ease. It
breaks either the handle or the bullet.
**************************************
> I found a bunch of Linotype @ .50 per lb. I don't think that
> this is the best, because a little too hard, alloy for .45 ACP
> defense use. Do you agree? Perhaps a 45% lead, 45% lino, 10%
> 50/50 solder might be a good place to start.
Linotype is a 475 F eutectic with 4% tin (Sn), 12% antimony (Sb),
and 84% lead (Pb). It makes the best looking bullet going but is
a waste of expensive tin. Alloy it with 50% lead and you will
have a great bullet alloy which will cast at about 14-15 BHN and
can be heat treated to about 22 BHN if desired. For non-magnum
pistol velocities even that 14-15 BHN hardness is not necessary.
For a softer alloy still, add more lead then bring the tin
content back up with solder. Do keep your tin content at about
2%-3% though, for good mold fill-out characteristics.
However, for a .45 defense load, the hardness, as relates to
bullet performance on the target, is not awfully important.
Velocities are too low for the .45 ACP to (dependably) deform in
flesh except for perhaps pure lead in a gaping cup point configu-
ration. Even then it is not be dependable unless the cup is
filled with grease. I have had reports sent to me that there
have been some colossal failures to expand by some of the recent-
ly introduced high hype pistol bullets when fired from close
range into water and water saturated paper.
Bullet nose shape and diameter is the key to bullet performance
in flesh for pistol velocities. The flatter, the larger diameter
the nose, the better the disruption. If there is a little metal
upset, so much the better, but do not count on it.
For a succinct explanation of this get Veral Smith's catalog. It
is filled with priceless tidbits. He is:
Lead Bullets Technology
HBR 62, Box 145
Moyie Springs, ID 83845
(208)267-3588
His catalog alone is an education in bullet fitting and loading.
********************************
> A friend has a Webley WG, and cast some bullets of lead with (I
> think) 5% antimony and 2% tin, to harden it up. When we fired
> the reloads, they were not very good. He bought some bullets of
> a softer alloy, and when we shoot these, they are very much more
> accurate than the others (like, they all get on the target!), so
> even a few percent makes a big difference.
The hardness of the alloy, taken by itself, is not necessarily
the controlling factor for good accuracy. It has been pretty
well established by serious cast bullet shooters that fit of
bullet to the revolver throat is probably the singular most
important factor (other loading practices being reasonable for
the type of loading being done) to accomplish good accuracy.
If the (cast) bullet is more than about .0005" smaller than that
of the throat, chances for good accuracy are diminished. This is
because gas cutting of the bullet, while it is still in the
throat, can destroy the integrity of the bullet and blow molten
lead ahead of the bullet where it will plate the bore.
Contrary to what some shooters believe, loads that lead the bore
can sometimes be cured by using a SOFTER bullet rather than a
harder one. This is because the softer bullet will more easily
bump up (obturate) to fit the throat than the harder one. This
obturation reduces or eliminates gas cutting. The softer alloy,
if not driven too fast, is more forgiving of oversize throats.
See "VELOCITY REQUIRED TO EXPAND OR DEFORM VARIOUS HARNESSES"
an Excerpt from "The Fouling Shot" Issue #81, Sep-Oct, 1989
"Match Wheelgun and Load Preparation, page 81" near end of this
article for alloy strength as regards velocities.
The reason for the reputation of hollow base wad cutter (HBWC) as
such an accurate projectile in so many guns is that its design
makes use of this knowledge. The soft skirt of the HBWC easily
deforms to fill the chamber throat so that there is virtually no
gas cutting. Remember, the HBWC is a target bullet, and
attempting to drive it too fast poses the possibility of blowing
off its skirt which may lodge in the bore.
As an aside, I have found one of the most accurate and
explosive .357 Magnum loads to be a reversed HBWC with a gas
check placed on what was originally its wadcutter nose. This is
not practical with all HBWC bullets because the nose is too large
to accomodate the gas check. I believe that mine are of Star
manufacture. These loads are driven hard with H-110 and W-W 296
and exhibit virtually no leading.
Your cast bullets are likely to be undersize for your Webley's
throats (a common situation) while the softer projectiles were of
larger diameter and/or were soft enough to obturate enough to
fill the throats adequately.
> Is there any danger associated with fumes in lead bullet cast-
> ing? Any common methods of protection?
Lead does not begin to out gas below about 1100 degrees F so the
danger is not from lead fumes. It seems that the danger from
lead is not very well understood by most casters in that quanti-
tative information does not seem to be available nor do we ordi-
narily have means to measure quantities. Prudence is therefore
the common sense answer to avoiding problems. I would not feel
comfortable casting in an unvented cellar, for instance, although
this has been a common practice in cold weather country and
places that have a winter. Here in San Diego, where the coldest
temperature is about 40 F, I cast in my open garage and feel safe
doing so. As a precaution, after casting many years I decided to
have my lead blood level checked. The normal city dweller is 11;
mine is 5.
A couple of years ago I read an account of a bullet caster that
had a dangerous experience with an unknown lead alloy that out-
gassed something that caused him to pass out for a while even
though he was in an open area. Some alloys such as lead plates
from modern batteries are to be avoided at all costs because of
the hazardous alloying materials. In the old days (late 1940's -
1950's) I used battery plates as nearly all my lead source.
A great deal of info is available regarding casting and alloy
hazards in the pages of The Fouling Shot (now The Cast Bullet).
Back copies of The Fouling Shot are available from:
Frank Stanard, Director of Services
7418 Ridgewood Avenue
Chevy Chase, MD 20815
******************************
Excerpt from "The Fouling Shot" Issue #81, Sep-Oct, 1989 "Match
Wheelgun and Load Preparation, page 81:
Correct bullet hardness for revolver target loads is about
8-12 BHN, depending upon the charge giving best bullet stability
and the chamber pressure generated.
The usable maximum chamber pressure of an alloy is a
function of its Brinell Hardness Number. As a rule of thumb,
optimum chamber pressure for adequate obturation without leading
is about four times yield strength. The conditions of firing in
a revolver are more severe than in a rifle, so this figure must
be taken as an absolute, though in a rifle this approximation can
be exceeded to about 5 times yield if everything is "perfect."
Within the range of alloy hardness we use for typical as-
cast or heat treated bullets (from 5-30 BHN), yield strength is
approximated by the BHN multiplied by 480. This means that a
soft alloy of 8 BHN, such as factory swaged lead bullets will
stand up to about 15,000 CUP (8x480x4=15,360), and an alloy of 12
BHN will stand 23,000 CUP.
This corresponds to the pressures generated by 4-6 grains of
fast burning pistol powders such as Bullseye, 231, Red Dot, Green
Dot or 452AA, which are all well suited for the .44 Spl. My
favorite all-purpose alloy is a mixture of indoor-range backstop
lead (mostly .38 wadcutter and .22 rimfire bullets) mixed with
about 1 part in 20 of Linotype to provide some minimal tin to
improve casting. This stuff makes a nicely filled out, soft
bullet of 11 BHN. Eric uses a similar alloy for his gallery
pistol loads. By the way, this soft alloy also shoots well in
moderate .30 cal. rifle loads up to about 1500 f.p.s., and is
without peer in the big bores, such as the .45-70.
The rest of this article is jamb-packed with other valuable tips
for improving revolver accuracy. It is posted in an effort to
convince you to become members of the Cast Bullet Association.
It's newsletter, The Cast Bullet, has more immediately usable
information in it in any given issue than ALL other gun periodi-
cals combined -- guaranteed! A great deal of the articles apply
to jacketed bullets as well as cast.
***************************************
VELOCITY REQUIRED TO EXPAND OR DEFORM VARIOUS HARNESSES
MINIMUM
TERMINAL HOLLOW *
BHN VELOCITY POINTS
*** ******** ******
30-50 2400 fps NR
20 2200 NR
18 1900 NR
14-15 1500 NR
10 1400 900 fps
8 1300 800
5(pure lead) 1200 700
NR - Not recommended for game shooting because of extreme
destructiveness. Good for varminting, though.
* - Hollow point size and bullet nose shape affect required
terminal velocity greatly, so these can only be considered
approximations. Hollow points are best used with pure lead or
tin-lead alloys as even small amounts of antimony cause bullet
break-up. If antimonial alloys are used, do not exceed 1 1/2%
antimony or 10 BHN.
***********************************
The 1991 Jan-Feb issue of the Fouling Shot has an article by O.H.
McKagen and Dennis Marshall entitled "On Lead-Tin Solders", page
89-8 through 89-14. It is the best explanation of bullet alloys,
their hardening, softening, time dependent characteristics (no,
that bullet that you cast last week is not the same bullet that
you have on your shelf today) that I have ever read. It puts
into perspective the nature of a number of alloys used for
cast/swaged bullets, time hardening, time softening, boundary
slippage etc., in words that the layman an understand.
The resulting knowledge can be used to give the caster/swager
more control over his bullets than he might have ever dreamed was
possible. It also helps one to recognize errors that often
appear in the glossy gun magazines when the writers presume to
relate their infinite wisdom to those (us) serfs who are
unread, unwashed -- you know the rest.
*********************************************************
ANOTHER CBA PITCH
There are a good many articles in the pages of the official
journal of The Cast Bullet Association that correct many of these
old errors.
Cast Bullet Association
Ralland Fortier
4103 Foxcraft Drive
Traverse City, Mich. 49684
$14.00/yr.
back issues, Index, etc. from:
Frank Stanard, Director of Services
7418 Ridgewood Avenue
Chevy Chase, MD 20815
***************************************
God Bless!
Norm