From: gmk@falstaff.MAE.CWRU.EDU (Geoff Kotzar)
Subject: Re: Slide staying back
Organization: Case Western Reserve University

In article <55034@mimsy.umd.edu> hes@unity.ncsu.edu (Henry E. Schaffer) writes:
#In article <54864@mimsy.umd.edu> ole@tosca.delab.sintef.no (Ole-Hjalmar Kristensen) writes:
## ...
##How do you manage to get Hoppes (No. 9) to get rid of lead quite well?
##In my experience it removes copper very well, but does not seem to
##work on lead. I mean, it seems to remove lead just as well as any
##other penetrating lubricant, but there is no apparent chemical action
##to get rid of the lead. The loose flakes are removed, but the stubborn
##spots stay.
#
#  I that there are several points.  I agree that #9 doesn't seem to have
#a chemical reaction with the lead, but the bronze bristle brush does
#have a mechanical effect on the lead, and then the patches wet with #9
#carries off the particles.  The big point is to avoid serious lead
#accumulation.

I wanted to make one point here. The original poster had stated that he had
good luck with Hoppe's removing lead in a .50 Thompson and a .45 black powder
revolver. The clue here is "black powder". Leading is rarely if ever a
problem with black powder guns. Patched round balls, as used in rifles, do
not allow the lead to contact the bore. The conicals also do not seem to
lead up the gun; now whether this is because of the large quantities of
lube that they carry or because the black powder shooter does not shoot
enough of them to allow for serious accumulation I do not know. I do not
personally shoot black powder revlovers but a close friend does and quite
extensively - affectionately known as The Crisco Kid. He does not see any
leading in his revolvers either. Again it may be because of the type or
quantity of lube or the lube combined with the black powder fouling. Now
Hoppes No.9 Plus does a very good job of removing black powder fouling and
if any lead that remained behind in the barrel happened to be mixed with the
fouling it would come right out as well.

I deleted a lot of useful info here.

#
#  Someone mentioned the need to get lead bullets with good lubes,
#and I agree.  However I've never had any problem with good brands
#like Bull-X, Allstar and Hornady.  Note that if you push a lead
#bullet fast enough (over 1,000 - 1,200 fps) that you generally will
#start to get serious leading.  That's where gas-checked bullets
#help, and finally at high enough speeds jacketed bullets are
#required.  (You need to reload to use lead bullets with gas checks,
#and you probably need to cast or swage your own to take full advantage.)
#
#--henry schaffer  n c state univ

I wanted to pass along a bit of additional info regarding leading problems
due to bullets of inappropriate hardness. I recently had a problem with
getting two friends started reloading. Both own GP-100's and were using
Penn bullets which I ran a hardness test on; the Penn bullets in question
were as hard as straight linotype. The loads I started them out with were
very light loads for .357's: 158 SWC's at 850 fps. One would not ordinarily
expect leading with such a hard bullet at such a mild velocity but they
were getting outrageous leading in the chambers and the breech end of the
barrel. After 20 rounds or so the groups opened up to 8 inches at 50 feet
and the rifling was almost totally obscured for the first inch or so of the
barrel. The leading was just as thick in the chambers and the only effective
way to remove it was to disassemble the gun and put it in a pan of mercury.

To make a long process painless we traced the problem to the bullets being
too hard for how fast we were pushing them. Because they were so hard they
were not slugging out under the low pressures and sealing the bore. As a
result there was serious gas cutting. The clue here was the leading in the
chambers.

When my friends shot my normal loads (Hornady 158 swaged SWC's over 6.5 and
7.5grains of SR 4756 in .357 cases) they never saw any leading accumulate
regardless of how long a string they shot. This is in spite of the fact
that the swaged bullets are much softer than the cast Penn's and the velocity
was higher (about 900 fps and 1100 fps repectively).

This is not to imply anything bad about the Penn bullets, they are great once
we get the velocity over about 1000 fps. Also in discussing things over with
Bob Palermo of Penn we found that they use a number of different alloys for
their bullets depending upon the intended application. Had I had my friends
buy the Penn full wadcutters they might never have seen this problem, also
had they been using .38 Special brass rather than .357 Mag brass the pressures
might have been enough higher to cause the bullets to slug out and fully seal
the bore.

My point here is that leading is not necessarily a problem of too soft a bullet
at too high a velocity. Depending upon the application, a harder bullet is not
always better.

geoff kotzar            gmk@falstaff.mae.cwru.edu

From: Norman Johnson <njohnson@nosc.mil>
Newsgroups: rec.guns
Subject: lead-bullet myths - here we go again
Date: 4 Oct 1997 23:19:01 -0400

Gentlemen and Fair Ladies,

Old wive's tales do persist!

#~while reading some postings here in the news-group I noticed
#~some mentioning the problem of lead build up. What is this ?
#~I also read that using lead-reloads(???) may cause the famous Glock kaboom
#~problem. What are lead reloads ? Is there a reason for not using lead
#~bullets?

#Lead is soft and it melts at high temperature.

It melts at 620 F.

#Softer bullets tend to have lower melting points and are more prone to
#leading.

Softer bullets contain more lead than harder bullets and melt at somewhat
higher temperatures than harder ones.  For instance, linotype, about the
hardest bullet alloy commonly used by casters melts at 474 F.  Most other
alloy mixes are somewhere in between that and 620 F.

#Currently the Oregon Trail stuff leaves behind the least amount of lead.
#The heat of the burning powder can melt lead and cause some to be left in
#bore, usually at the breach end.

 From available evidence, the above cannot be demonstrated.  Examination of
unprotected bullet bases after firing nearly always shows powder peening but
no evidence of melting, nor even significant softening.  The heat is in
contact with the bullet base for about 3 milliseconds during a typical
launching scenario and the heat transfer characteristics of lead/lead alloy
bullets simply do not allow enough heat transfer to accomplish melting
during this brief encounter.

Lead deposited in the breach end is principally from gas cutting.  Due to a
poor gas seal, the gases jet past an undersized bullet, especially along the
trailing edges of the lands.  This gas cutting can be virtually eliminated
by proper bullet fit.  No matter how hard the alloy, an undersized bullet
will lead the bore.

Contrary to conventional knowledge, leading can often be minimized or
eliminated by using a SOFTER, rather than a harder bullet.  This is very
often the case when hard but undersized bullets cause leading.  The softer
alloy offers the advantage of, upon ignition, bumping up to fit the throat,
thus providing the very important gas seal.

>As the bullet travels down the barrel the rifleing twists the bullet up to
a >speed that will spin stabilize it in flight.   The inertia of the bullet
>resists this twisting action, and in  cases where the resistance overcomes
>the hardness of the bullet the bullet will strip off the rifleing and
leaves >gobs of lead in the bore.

Whether bullets strip the rifling has been a long running discussion.  Some
hold that it is impossible and have put forth pretty convincing evidence in
the form of computer models of materials and the forces induced during the
acceleration scenario using finite element analysis; along with samples of
actual bullets fired at high velocities.  Others have submitted photographic
evidence of the stripping, some of which has proven to be gas cutting
induced when examined closely.  However, stripping has not been associated
with leading.  The point here is that stripping is not a problem for those
who use a little prudence in their alloy selection, and is certainly not a
leading concern.

>The amount of leading also varies with the quality of the lube on the bullet.
>Most use some variety of wax that melts and provides lubrication while the
>bullet travels down the bore.

The function of bullet lubes is not yet understood by the
shooting community - that is why lubricant development for bul-
lets is a empirical rather than by design.  It is interesting to
note that really good lubricants, as judged by traditional engi-
neering standards, seldom make good bullet lubes.  It seems that
waxes or a high level of wax makes the best bullet lubes.  Be-
cause wax viscosities are so temperature dependent, a change in
ambient temperature results in, effectively, a "different" lu-
bricant, and, at least theoretically, different performance.

There is recent evidence that bullet lube may not serve any practical
purpose in at least some types of shooting.  People like Ken Mollahan from
the CBA have documented experiments using dry cast bullets at 2000 fps or so
where no lube was used and no leading was experienced.  This may sound like
heresy to the old timers like me, but as we learn more about what makes
non-jacketed bullets shoot well, many of the old wive's tales fall away.

My own shooting with up to magnum pistol velocities has convinced me that
lube is a waist of time, material, and money.  I routinely load non-lubed
bullets (8 BHN; pretty darn soft) for all my target loads now.   This does
require that the bullet fit the throat well, however.

                 *************************

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.

                 *****************************

God Bless!

Norm