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The Lee Lead Hardness Testing Kit
and Other Bullet Biting Alternatives
By
Joseph D'Alessandro Editor
| RealGuns.Com
 In the old days, if
you wanted to know the hardness of lead, or the legitimacy of gold
currency, you bit the object. Then you'd take stock of how much your
jaw hurt, the depth of your teeth marks in the object, and arrived at
a conclusion - probably that we were in need of a good dentist. When
you purchased ready made bullets or ammunition from Wild Earl's
Flying Lead Emporium you assumed Earl, or one of his minions,
conducted at least the same comprehensive testing. Eventually, the
reliability of some tests and the legitimacy of others were called
into question when cast bullets occasionally melted in boxes on warm
days or penetrated tank armor. An inability to test lead hardness
when casting bullets from alloy of an unknown source is a handicap,
not unlike the blind spot that exists when handloading ammo
without the ability to measure pressure - it can be done, but most
people are kidding themselves when they believe they can estimate
either of these factors without proper tools to periodically
substantiate the results. Cast bullet hardness effects handload
pressures, barrel leading and terminal ballistics in terms of
penetration, retained weight and wound channel.
Oh, those wacky Swedes
Somewhere between 1882 and the Paris Expo of 1900,
Johan August Brinell, an employee of Sweden's Fagersta Ironworks,
devised a metal hardness test which he thoughtfully named after
himself. Alright Johan! In concept, material hardness is its quantified resistance to plastic
deformation. Brinell Hardness is determined by forcing a hardened
steel or carbide ball of known diameter under a known load into a
material's surface and measuring the diameter of the indentation
with a microscope. A Brinell Hardness Number is obtained by dividing
the load, in kilograms, by the spherical area of the indentation in
square millimeters. Alternatively, for $35, the process can be
made a whole lot simpler with a Lee
Hardness Tester. The Lee tester is comprised of (Above L-R) a calibrated hardened steel ball indenter, a V Block
Cradle and a 20x optical microscope.
But when I shake it, I hear stuff moving around
inside...
 Looks
can be deceiving. What looks like a die with a fixed ball point tip,
is actually a an indenter ball that is preloaded with a spring
within the indenter housing. When inserted in a reloading press, and
placed under controlled load against lead alloy being tested, 60 lbs of force
are exerted.
Commercial Brinell test equipment would commonly
utilize a 10mm indenter ball and the load force would be 500 Kilograms.
Unfortunately, 10mm is as large as, or larger than, most lead bullets
and it would be necessary to keep a gorilla in a cage to apply the
force; and arrangement that might not be practical in a home shop.
By proportionally scaling down the ball and the force, Lee Precision was able
to package a perfectly accurate and practical tester in a small
package. I measured the steel ball to be approximately .156" in
diameter, a sized reduced from typical which allows a corresponding
reduction in force to 60 lbs, a combination easy to handle in a
reloading press.
"But it must be complicated to use!". Glad you
asked, stranger...
It takes only a few minutes to set up the tester. The
Indenter is screwed into the die holder, the installed height is not
critical as long as the indenter ball can reach the test bullet. The V Block slips into
position like a shell holder, although I found I had to remove the
retaining spring clip from the ram. This last step was not required
with my turret press.
Instructions for the tester indicate a flat is to be
filed on the side of the test bullet for a contact surface. The initial
bullet I tested was a Cast Performance item advertised as heat treated to
a BHN 16~21. I wasn't sure how deep the heat treating
went, and I didn't want to remove too much material and get an
erroneous reading. For reference,
wheel weight alloy has a BHN of 9, linotype has a hardness of BHN
22, pure lead is BHN 5.
Heat treating is an easy way to get to a surface hard
cast from a softer alloy recipe. The radius of the .458"
bullet is large so there is plenty of surface for the indenter ball
to make contact, however, I did take two measurements; one without
the flat and one with, so I could compare the two and see if filing
away the surface made for a different BHN result. The flat cut
was approximately .008" deep and the readings were the same. Lee
cautions to never check hardness at the base of a bullet as this
surface is frequently significantly softer than the sides or nose.
The base is typically used to the support the bullet in process,
such as hardening, and may not be subjected to the same temperatures
and treatment.
Controlling applied force...
 The indenter housing has a through hole in the
retaining cap.
As pressure is exerted on the indenter ball, it compresses against
the
internal spring, pushing the indenter ball shaft up through the hole
in the retaining cap. When the end of the indenter ball shaft is flush with
the cap, it is held in place 30 seconds. The approximately 60 lbs of spring pressure
is pretty easy to overcome with the mechanical advantage of the
reloading press, care must be taken not to apply too much
pressure. Generally, more than 1/64" shaft protrusion through the retaining
cap means the indenter ball was too heavily loaded and the test in invalid.
I checked perhaps 20 - 30 bullets and did not encounter this
problem.
Like reading isn't hard enough...
The indent left by the process in the test bullet is small enough to require a
magnifying optical comparator to measure its size. The included
20x microscope contains a scale reticle, not unlike the one
that appears in a range finding rifle scope, that is used to acquire
this measurement. The scale is .100" long and is divided into
.002" increments.
The operator puts the nose of the microscope against
the bullet, over the indentation, with the open side of the tip
facing up to gather light. The reticle scale is then placed to
overlay the indent, like a miniature ruler, and a measurement is
taken. The measurement is than compared to the enclosed conversion
chart and the corresponding BHN.
 The
"Brinell Hardness and Maximum Pressure Chart", checked by
calculation, provides very accurate conversion information from
indent measurement to BHN and, with access to a certified digital
scale that will cover the 60 lb applied force range, it is pretty
easy to check tester calibration. The only piece of information in
the chart I might question is the "Max PSI" column. I am not sure
if the reference is an issue of gas cutting, or bore leading.
According to the chart, a very popular #2 alloy carries a 16 BHN,
has a strength indictor of 22,703 PSI and should be limited to
20,000 PSI as maximum pressure. Wheel weight alloy with a BHN of 9
carries a strength of 12,748 PSI and a MAX pressure rating of 11,473
PSI. The terminology is a little vague. Is this peak, max average,
sustained for some period of time? I assume, because there is no
reference to terminal velocity, this is a material yield strength
and based on calculation; single digit odd numbers at the end of a
number expressed in multiple tens of thousands. I believe this
portion of the information isn't particularly authoritative in
determining limitations*.
(* While the slip sheet does not present the detail
behind the "Max PSI" entries, the basis is well defined in detail in
"Modern Reloading" 2nd edition Chapter 10, page 129. Many thanks to
RPJ for bringing this to my attention. Comment Added 10-13-05)
What are typical hardness levels?
On the left are examples, L-R of Oregon Trail Bullet
Company's Lasercast, Cast Performance and Meister bullets.
They are good quality product that I probably push a little more
than intended and have not had bullet failures or excessive leading.
The BHN value is:
Oregon Trail Lasercast BHN 16.6
Cast Performance BHN 20.9
Meister BHN 16.6
I checked some of my own recycled wheel weight
bullets with some added alloy for hardness and they came in at 14.4.
My oven heat treated hard cast bullets were in the 27-28 range
depending on lot tested. I use the latter in full tilt 45-70
loads and knock around 358-378 RG loads.
I'm not really making a pitch for certain hardness
levels, I think that selection should be dictated by a shooter's
experience and the specific application. The point is, the Lee
Hardness Tester puts more control in an individual's hands; better
control of bullet casting projects, verification of purchased cast
bullets and better assessment of what works, or not, when hunting or
target shooting. An excellent product and a typical Lee value.
Some related information on Real Guns:
Casting bullets and
selecting fire extinguishers Part I
Casting bullets and selecting fire
extinguishers Part II
Casting bullets and selecting fire
extinguishers Part III
Casting bullets and selecting fire
extinguishers - Conclusion
45-70 Cast Bullet Handloads
45-70 Cast Bullet Handload Data
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