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.he CHAPTER 2 CORBIN HANDBOOK AND CATALOG NO. 7, PAGE #    

                              MAKING THE LEAD CORES

          The  two  main components that go into most bullets are  the  lead 
     filling,  or core,  and the outer skin,  or jacket.   We'll talk  about 
     jackets in the next chapter.  Right now, let's make some cores.
          There  are  two main sources for lead cores.   You can purchase  a 
     spool  of lead wire in the proper diameter,  along with a core  cutter, 
     and chop off accurately-measured lengths.  Corbin has lead wire in pure 
     175,000  grain spools (LW-25),  and the PCS-1 Precision Core Cutter  to 
     cut  them.   The core cutter has an adjustable stop screw that  adjusts 
     the amount of lead cut on each stroke of the tool.  
          The  second source is your own supply of scrap lead,  the same  as 
     you might use for bullet casting.   Corbin makes a 4-cavity, adjustable 
     weight core mould that mounts to the reloading bench.   You don't  have 
     to  pick  it  up,  and there are no handles  required.   Four  pistons, 
     precision  fitted  to four cylinders,  slide up and down to  eject  the 
     cores.   The bottom position is set by a rest plate.   This steel plate 
     rests on a pair of nuts, fastened to two threaded rods at either end of 
     the mould.  
          Adjusting  the nuts upward decreases the volume in the  cylinders, 
     and gives you a lighter core.   Pouring molten lead into the top of the 
     mould  fills all four cavities.   Moving a long sprue cutter chops  off 
     the lead at the top of the cavities, leaving even lengths of lead to be 
     ejected  straight  up from the cylinders.   The process is  very  fast, 
     making it possible to produce at least 1000 cores per hour.
          Lead wire can also be manufactured at home.   Corbin makes a  lead 
     wire  extruder  kit for the Hydro-press,  capable of making lengths  of 
     lead  wire  from lead billets.   Lead wire can be extruded  in  special 
     shapes, as well, for use in stained glass work or as hollow tubing used 
     for fishing sinker wire.  The LED-1 Lead Extruder Die set comes with  a 
     selection  of popular diameters of interchangeable dies,  all of  which 
     fit into a master body.   Included with the kit are billet mould  tubes 
     to  form  the proper diameter of lead cylinders  for  extrusion.  These 
     special forms can be the basis of additional income for the Hydro-press 
     owner.   Hand  presses  do  not  have sufficient stroke  or  power  for 
     commercial lead wire extrusion.  
          Small diameter lead wire for the sub-calibers (.14,  .17, and .20) 
     can be produced in the Corbin hand presses with the LED-2 extruder kit.  
     Only relatively short lengths are made at one time,  but they are  very 
     economical sources of cores for the tiny sub-caliber bullets.  
          For  those  who wish to make commercial quantities of  lead  wire, 
     Corbin manufactures the EX-10 lead wire extruder,  a dedicated, single-
     purpose  machine to produce any size or shape of lead wire in 10  pound 
     spools.   The EX-10 uses lead billets of 2-inch diameter,  which can be 
     cast  using  Corbin's tube moulds.   Write for specific information  on 
     this product.
          Lead  wire  for  bullet cores can be used in  two  ways,  and  the 
     diameter depends on what way you plan to use it.   You can simply swage 
     the lead into a finished bullet,  with no jacket.   In that  case,  the 
     lead  only has to slip easily into the smallest die bore in the set you 
     are  using.   Dies made only for lead bullets are at final diameter  of 
     the  bullet,  and consequently your lead core should be just  a  little 
     under bullet diameter.
          If  the lead is too small in diameter,  it will stick out the  die 
     mouth before you have enough of it to make the weight you desire.  That 
     is a situation to avoid -- never apply any pressure to a component that 
     isn't  completely  contained within the die.   The punch will  probably 
     slip  off to one side and be damaged by striking the mouth of the  die. 
     The  exact diameter isn't important as long as the core fits  into  the 
     die easily and doesn't stick out the die mouth.
          But  if you want to make a jacketed bullet,  then the core has  to 
     fit  inside  the jacket (obviously!).   You cannot start  with  a  .357 
     caliber  lead bullet and somehow "put a jacket on it" to wind up with a 
     .357  caliber jacketed bullet.   Instead,  you use lead wire or a  cast 
     core that fits inside the .38 jacket,  and expand it upward in the die.  
     The lead pressure expands the jacket right along with it,  resulting in 
     a tight, uniform assembly.  
          The  walls of a .357 or .38 caliber jacket are usually about  .017 
     inches  thick.   There  is a wall on both sides of the  core,  and  the 
     jacket  normally  is made small enough so that it will  work  for  .355 
     (9mm)  as  well  as  .38 caliber.   Bullet jackets  are  almost  always 
     considerably smaller than the final bullet diameter so that they can be 
     expanded upward from core seating pressure.
          This  means  that you have a jacket with an  outside  diameter  of 
     about  0.354 inches,  minus two walls of 0.017 inches,  for a remaining 
     inside  diameter of about 0.320 inches.   Better quality  jackets  have 
     tapered walls,  so that the base is even thicker.  In practice, a 0.318 
     inch core will fit inside most .38/.357 caliber jackets properly.
          But for higher precision, a die set for the Corbin presses usually 
     includes a separate core swage die, which accepts the raw lead core and 
     reshapes it to a more perfect cylinder,  flattens the ends nicely,  and 
     expands  the core diameter very slightly in the process.   The die also 
     extrudes a small amount of lead from the core to adjust the weight.
          Because  of this extra die,  it is necessary to use a bit  smaller 
     diameter of core.  A 0.312 inch lead core fits nicely into the standard 
     0.315 to 0.318 inch core swage die, allowing for any bending or denting 
     that the core might receive in handling.   And that is how we arrive at 
     the  proper diameter of lead wire to use for any set of  dies,  in  any 
     caliber.   For jacketed bullets,  the core must fit into the jacket and 
     it  must  also fit easily into any core swage die that is part  of  the 
     set.   For lead bullets,  the core must at least fit into the final die 
     and not be so long that it sticks out the die mouth.
          In  the CM-4 Core Mould,  six diameters cover most of the  bullets 
     you  might  wish to make.   The .224 mould makes a core of about  0.185 
     inch diameter, which works well in the 6mm and .25 as well as the 6.5mm 
     caliber.  The .257 caliber mould crosses over slightly into the .25 and 
     6.5mm  caliber range,  but since different jackets have different  wall 
     thickness,  it is useful for thinner wall .25 jackets and thicker  wall 
     .270 and 7mm jackets.  
          The  standard  7mm jacket takes a 0.218 inch core,  so a 7mm  core 
     mould  is made in that size.   The .30 calibers all take a  0.250  inch 
     core,  as  do  most of the .32 and .338 jackets.   Heavy walled  tubing 
     jackets in large bores can use the same core size as a standard  jacket 
     might in a smaller caliber.  A pair of standard sizes cover the .38 and 
     the   .44-45   calibers.    These  are  0.312  inch  and  0.365   inch, 
     respectively.   A slightly smaller size is made for the .41 caliber and 
     the .40 Bren 10 caliber.
          Using  the next smaller size normally serves quite  well,  without 
     the expense of having a custom mould built.  However, custom moulds CAN 
     be  made  to order if desired.   For large diameters  of  lead,  Corbin 
     builds  special moulds to order at a correspondingly higher  cost  than 
     the  CM-4.   Moulds  for billets of half inch diameter can be used  for 
     shotgun slugs.   Tube moulds,  which have a steel base with a plug that 
     slips  into the bottom of a honed steel tube,  are generally  used  for 
     large diameter billets.  
          Lead cores are discussed in great detail in the book,  "REDISCOVER 
     SWAGING".   The advantage of using a lead core mould is the lower  cost 
     of using scrap lead.  The advantage of using lead wire is the neatness, 
     safety,  speed,  and  ease  of use.   There is not much  difference  in 
     potential  accuracy.   Lead  wire  has a slight edge  over  cast  cores 
     because of the great uniformity of the extruded product. 
          You  probably wonder about the hardness of the lead:   can you use 
     wheelweights, or casting alloys to swaging bullets?  The answer depends 
     on  the caliber,  and the system of swaging you plan to use.   In  most 
     reloading press dies, you can't quite generate enough pressure to swage 
     any  lead  harder than about Brinnell Hardness 8 (or  about  3  percent 
     antimony/lead alloy) before breaking either the die or the punch.   But 
     in  certain  circumstances,  you  can  even swage  linotype  alloys  of 
     Brinnell  Hardness 22.   The Corbin Hydro-press can swage any alloy  of 
     lead ever made, or even solid copper if you wish.  
          The reason that you can swage hard alloys in some calibers and not 
     in others,  in some shapes and not others,  and in the Hydro-press  but 
     not  in  a reloading press has less to do with the power of  the  press 
     than it does the strength of the dies and punches.   If you are curious 
     about the mathematics involved in engineering dies to withstand certain 
     pressures,  the  book  "POWER  SWAGING"  is  full  of  revealing  data, 
     formulae, and charts that will make it all clear. 
          As a rule of thumb,  it's safer to use soft, pure lead for swaging 
     in  all  circumstances  because pure lead flows more  easily  at  lower 
     pressures,  and thus puts less strain on the dies.   But, if you have a 
     need to swage hard lead for some reason,  don't give up just because of 
     a  rule  of thumb!   We have a way to do it in every case,  if you  are 
     willing to purchase the correct kind of tooling.  Your stock of casting 
     alloys can be used if the caliber,  die,  and press system is  selected 
     with  proper specifications for hard lead.   Tooling made for hard lead 
     may,  in some circumstances,  not be as useful for soft lead because of 
     the  different size bleed holes.   That is one reason why you  need  to 
     talk  to the die-maker before jumping in head first with a bar of  hard 
     alloy in hand!  
          If  you  use Hydro-press dies,  hard lead is perfectly  acceptable 
     in calibers up to .500 diameter,  unless very deep and thin base skirts 
     or other special designs are planned.  The dies are so strong that they 
     can handle any lead alloy.  In the Mity Mite system, hard alloys can be 
     handled  if the die-maker knows in advance you plan to  use  them.   In 
     calibers  above .358 diameter,  they are a bit risky because of the die 
     wall  in  the smaller Mity Mite series -- an imprudent  stroke  of  the 
     handle  could crack a .45 caliber die used with too hard an alloy.   In 
     the  reloading press,  calibers of .243 and .224 work  reasonably  well 
     with  hard  lead,  but  anything larger should be used with  alloys  of 
     Brinnell  Hardness 6 and under.   Corbin supplies pure lead in  billets 
     and  in  lead  wire form,  but does not furnish alloy  lead  except  on 
     special order.
          A  potential objection to lead wire is the cost of  shipping.   At 
     the  time of this writing,  it costs about $10 to ship a spool of  lead 
     wire completely across the country.   A spool of .22 caliber wire makes 
     over 4,000 .224 bullets.   The cost of shipping, then, breaks down to a 
     mere 0.0025 cents per bullet (that is a quarter of a penny per bullet).  
     This amount is not prohibitive,  and consequently most people choose to 
     use  lead wire for the smaller calibers.   In the larger calibers,  the 
     cost  per  bullet increases since there is more lead consumed  in  each 
     bullet,  but the trade-off of convenience and safety still results in a 
     majority of bullet-makers using lead wire.
          Corbin has lead billets in 0.795-inch diameter for use in the LED-
     1  extruder  die  (in case you don't care to  cast  billets),  and  can 
     furnish lead in just about any size of billet.  Alloys can be furnished 
     only  in minimum lots that generally are 100 to 250 pound,  because  of 
     the minimum billet required for a commercial extruder operation.   Many 
     of  our customers can provide you with the smaller quantities of  alloy 
     leads:   check  the  "WORLD  DIRECTORY  of CUSTOM  BULLET  MAKERS"  for 
     addresses and phone numbers.