From: njohnson@nosc.mil (Norman F. Johnson)
Newsgroups: rec.guns
Subject: tempering
Date: 13 Feb 1996 17:26:56 -0500

Rich, 

# I have read a little about cast bullet tempering using a stove in 
# the Lyman Pistol and Revolver handbook and will like to hear from 
# others on this subject if you have tried it.

# Will use of the kitchen oven, be dangerous to my life (RE: Wife)??
# In all seriousness what are the hazzards of lead fumes in the same
# oven as I use for day to day cooking ?

# Is it best to temper before sizing or after, I have just pur-
# chased a Star sizer this weekend and I am guessing that that this 
# baby can handle just about anything!

# My main reason for this is leading in the forcing cone and barrel 
# of my S&W Mod 66.  I also notice slight problems with my wife's 
# P220 in .38 Super but not as bad, while my .45 Gvt. has no prob-
# lems at all. All casts are made from the same mix and at the same 
# time. I have just re-cut my Mod.66's forcing cone to 11 deg. and 
# I hope this will solve most if not all of the problems.  

Random thoughts and findings:

I suspect that by tempering you mean heat treating/hardening.  
Bullets are usually hardened by oven heat treating, which leaves 
them as hard as that particular batch of alloy can attain.  It is 
accomplished by heating cast bullets to just under their slumping 
temperature, then quenching quickly in water. 
 
Tempering is reducing hardness after hardening.  Tempering is 
used to bring the bullets down to a reduced hardness level as is 
required for one's shooting requirements.  This is done by bring-
ing the bullets up to some temperature in the oven then allowing 
to cool slowly.  

The Cast Bullet has had numerous articles over the years on doing 
both heat treat hardening and tempering.   

There is no danger in using the same oven for heat treating and 
bullet processing.  This has been checked by CBA members with 
sophisticated equipment and written up in detail.  Many of us 
have done it for years.  Lead outgasses at about 1100F and poses 
no threat at casting-heat treating temperatures.

You may very well find that your bullets shoot better with no 
sizing at all.  My bullet sizer is virtually retired these past 
10-15 years.  The reason is that most bullets, as they fall from 
the mold, are undersized for modern production revolvers.  Here 
is why:

In a revolver the throats are the areas in each cylinder chamber 
immediately ahead of the portion of the chamber where the brass 
case rests and into which the bullet projects.  If the bullet is 
sized so that it is a gentle force fit in the throat, all else 
being equal, your accuracy potential will increase greatly.

Two factors come into play here to improve potential accuracy:

a) the bullet axis is more nearly coaxial with the barrel axis.

b) gas cutting, which will positively RUIN accuracy, is virtually 
eliminated.
 
Despite what the gun writers say, my tests show that there are no 
observable pressure increases when using bullets up to .006" over 
barrel diameter. 

My Blackhawk came with .4545" throats and a .449" bore.  That is 
a rediculous mismatch, yet I shoot .4540-.4545" bullets in it, in 
both target and "boomer" 350 grain hunting loads, and it is as 
accuracate as any revolver I know.  However, if I use 
standard .452" bullets, it shoots all over the countryside. 

Using an old C-H Swage-O-Matic bullet swaging press and appro-
priately modified (opened) dies I am able to reshape and resize 
most pistol bullets, including most of my cast bullet rejects, to 
useable and usually very accurate projectiles.  If one does not 
require that the increase in diameter exceed a couple of 
thousandths, and the bullet is not too hard, (no jacketed bullets  
here) a  bullet sizer with the appropriate die can sometimes be 
use to "bump up" a given bullet to proper size altho this does 
not provide the same control and consistancy as  bullet swaging 
equipment.  Be careful tho, it's easy to break the sizer handle.

Book after book has been written about revolver/cast/swaged 
bullet accuracy, some of them containing highly misleading mate-
rial.  For anyone seriously interested in revolver accuracy, The 
Fouling Shot, published every other month by the Cast Bullet 
Association is INVALUABLE!  These are people who DO it, not just 
talk about it.  I have improved a Redhawk .44 Magnum from a 
"best" of 2" at 25 yds. to a constant .75" at the same distance 
by changing bullet diameter.  Now THAT'S satisfying!!!

Measure the throat diameters and slug the barrel.  If you      
have a gun that has throats smaller than the groove diameter, 
(fortunately, an infrequent condition) there is not much hope for 
reasonable accuracy.  Revolvers will not tolerate an undersize 
lead bullet rattling down the bore.  

Your forcing cone leading is very likely because your cylinder 
throats are oversize, not because your alloy is too soft.  In 
fact, sometimes, for a given powder charge, a softer bullet will 
shoot more accurately because softer alloys will allow for more 
complete obturation (bumping up) and reduce or eliminate gas 
cutting.  

Lately I have been working with .38, .44, and .45 target loads 
using NO bullet lubricant.  When my bullets are fitted for an 
easy force fit into the chamber throats, there is no observable 
leading after 60 rounds.  The sixty round figure is because I 
have just begun these tests and have not fired more than 60 
rounds at an outing.  

When you slug your barrel, note if there is a tight spot or area 
anywhere in the barrel.  PAY PARTICULAR ATTENTION TO THE BACK OF 
THE BARREL WHERE IT ENTERS THE FRAME.  A tight spot here IS 
COMMON and can size down your bullet just as an undersize throat 
can.

The 11 degree forcing cone can help accuracy; but only if the 
basics are known and followed.  

Sorry that this got so long; hope it helps.  

God Bless!

Norm

From: njohnson@marlin.nosc.mil (Norman F. Johnson)
Newsgroups: rec.guns
Subject: Re: [Reloading] How fast for hard cast?
Date: 2 Feb 1997 10:56:44 -0500

Jeff,  

# I was reading the current issue of Handloader, and one of the writers
# was commenting on hard cast lead bullets.  He stated that most bought'n
# hard cast bullets are so hard that they do not obturate (upset to fit the
# bore) well at 1000 f/s or less, and can lead even worse than swaged
# slugs.  Which brings up the question (which he thoughtfully didn't
# address), how fast is fast enough for hard cast bullets?

He was absolutely correct:
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