corbin rbtl-5 User Guide

How to Swage Bullets Using The

RBTL-5-M, -S, or -H Die Set

Type -H dies fit into the ram of the Corbin Mega-Mite press (CSP-2), Corbin
Hydro, Jr., (CSP-2H) press, and the Corbin Hydro-Press (CHP-1). The type -M
dies fit either the horizontal Silver Press (CSP-3) or the vertical Series II Press
(CSP-1). The type -S dies fit only the Series II Press (CSP-1). The last letter, ­M, -S, or -H, describes the outside diameter, threads, punch lengths, and which
presses the die set will fit. If a tool fits both the -S and the -M systems and
there would be no difference in it for either of them (such as punch holders or
draw dies), then the -M designation is used.

The 5-die set consists of a CORE SWAGE (CSW-1), a BOAT-TAIL PREFORM
(B-1), a REBATED BOATTAIL FINISHER (B-2), a POINT FORM (PF-1) die,
and a LEAD TIP DIE (LT-1) each with one internal and one external punch,
except the two rebated boattail dies share the same external core seating
punch.

External

Punch

Internal

Punch

CSW-1 B-1 B-2 PF-1 LT-1
(additional flat base punches also shown,
not included with 5-die set)

An EXTERNAL PUNCH is held in the FLOATING PUNCH HOLDER (FPH-1­M or FPH-1-H), which comes with the press and screws down into the top
plate of the press. For the -M and -S external punches under 3/8-inch caliber,
a threaded bushing and steel ring are removed from the bottom of the punch
holder, placed over the external punch, and then screwed back into the bot­tom of the punch holder to secure the punch. The punch holder screws into
the press head, so the punch faces the ram. For -M and -S punches from 3/8­inch up, the bushing and ring are part of the punch assembly. For -H external
punches, only a threaded bushing is used, without the steel ring. The external
punch is the TOP punch in these systems.

The die screws into the press ram, with its INTERNAL PUNCH inside the
ram. Some -H internal punches require the use of spring powered retraction:
for the PF-1-H die, the internal punch is called an EJECTION PIN punch, and
it will have a quarter inch diameter hole through the head portion, through
which a 1/4-inch diameter retraction pin fits. The pin goes below the large
spring around the press ram, and pushes down on the pin, which then pushes
the punch down when the ram is raised, making it easier to insert material
into the die. For the PF-1-M and PF-1-S dies, a notch is machined into the
head of the internal punch, which matches a removable pin with knurled head
pushed into the front (CSP-1) or top (CSP-3) of the press. This is the STOP
PIN. It presses on the tail all punches except for the ejection pin punch, to
cause ejection on the down stroke. Because the PF-1 die would form the bul­let around this pin if the pin were allowed to remain in the die cavity during
swaging, the stop pin must be put into the notch and used to keep the pin
retracted from the cavity during swaging, holding it firmly during the down
stroke to cause ejection of the bullet.

In the -H system, a knock-out or ejection bar goes through a slot in the press
ram, below the spring and also below the retraction pin (if one is required
not all punches have a hole through the head). The knock-out bar supports
the head of the internal punch while the component is being swaged, and
comes to rest on the press mounting plate on the downward stroke. This stops
the movement of the bar while the ram continues down, making the punch
stop moving while the die goes down with the ram.

Floating Punch

Stop Pin

(CSP-1 or

CSP-3 press)

fits the slot in

the ejection

pin punch

head.

New style punches do not require
the spacer ring. Their head is twice
as long as the previous design.

Diameters larger than about .375
will use a captive hex-bushing and
semi-removable head (factory
assembled, no need to ever take it
apart once it has been tested).

External

Punches are

held in the

press HEAD

using the

Holder.

External

RBT PF

Punch, is

used ONLY

to push the

RBT bullet

into the PF

die. Any

other use

may

destroy it.

PF-1
Point
For m

Die

Internal
ejection

pin

punch,

PF

The RBT deflects

muzzle gas so it

does not focus in

front of the bullet,

as with the

standard boattail.

Never try to swage a component that will not go into
the die by hand. The swaging operation depends on each
component being slightly smaller than the die bore, and
increases the bullet diameter a little with every step.

The first die is the CORE SWAGE (CSW-1). It is
used to form a piece of lead to precise diameter, length and
weight. There are three bleed holes through the sides of the
die, and its punches are very close fits to the die bore. They
are the smallest punches in the set and only fit this die prop­erly. Always make sure the punch fits the die by hand be­fore applying pressure to it with the press!

For power presses, set the bottom sensor so the pres­sure stops (red LED on the sensor goes on) just as the
swaged core is ejected (internal punch even with the top of
the die). Use a knock-out bar that allows the punch to come
just to the die face, if you have more than one height of bar
with your press (CSP-2 hand press uses different heights of
bars for various punch and die lengths). Make sure your
hand press is in the SHORT STROKE (swaging) position:
the CSP-1 and CSP-2 presses have dual stroke pivot holes
for the ram/toggle linkage and you cannot swage in the long
or reloading stroke (it may break the stop pin to try).

You can use cut lead wire, or a cast lead core. Apply a
small amount of Corbin Swage Lube to the cores as you
handle them. Set the floating punch holder so the desired
amount of lead is left in the die when the press stops mov­ing up (position of the top sensor controls top of stroke on
hydraulic presses, physical end of ram travel is fixed on hand
press). Always extrude at least 1-2 grains from each core,
or else you will not achieve consistent weight control.

After making the desired number of cores, clean them
in hot water to remove the swage lube, then let them dry
and insert them into bullet jackets (if jackets are used).

The B-1 Boattail Preformer is the second die in
a RBT die set. It will accept the jacket for its caliber easily
but closely, and has no bleed holes. The B-2 looks similar,
but is marked with the BT-2 designation. The bore size of
the B-1 is slightly smaller than that of the B-2. The internal
punch for the B-1 die is a loose fit in the die; it serves ONLY
to push the bullet out, and plays no part in forming the base.

Select a diameter of external punch that fits the jacket
ID at the point where you want the core to be after seating.
Thicker jackets, and lighter cores in tapered jackets, both
require a larger diameter external punch than thinner jack­ets or heavier bullets with a tapered commercial jacket. (See
Corbin Handbook for discussion of proper core/jacket/
punch fitting).

The correct core seating pressure is normally in the
300 to 500 PSI range. Follow any written instructions pro­vided with the die regarding the suggested pressure. Always
start with the pressure in a low setting on the hydraulic
presses (300 to 500 psi) and increase slowly until the jacket
expands to just under the diameter you get with a swaged
pure lead slug in the die. Any greater pressure than this will
only stress the die and could bend punches or break dies.

Apply a small amount of swaging lube to the outside
of each jacket as you pick it up to insert in the die; the
amount that you get by rolling a drop between finger and

thumb is sufficient in most cases. Lubricant should not be
allowed inside the jacket.

The third die is the REBATED BOATTAIL FIN-

ISHER (B-2). Note that the combination of the BT-1, BT-2,

and the external RBT punch for the PF-1 die is also packaged
as the RBT-2 ADD-ON SET, for adding the RBT design to ex­isting flat base die sets. Use the same external punch (core

seating) that you used with the previous step. Push the bul­let base first into the die, and apply enough pressure so that
a shoulder is formed clearly at the junction of the boattail
and the bullet shank (full diameter portion). Use little or no
additional lube: a build-up of lubricant at the edge of the
punch will prevent forming of a sharp edge. Do NOT con­tinue to apply more pressure if the edge is not sharp: wipe
the punch clean of lube first!

The fourth die is the POINT FORMER (PF-1). It
shapes the ogive curve on the bullet and gives the bullet its
final diameter. This die has a bullet-shaped hole. The diam­eter of the point form die itself is designed to match the
core seater, the jacket material and thickness, and the lead
hardness. Using materials other than those for which the
set was designed can change the bullet diameter and may
cause the bullet to stick or become hard to eject.

The external punch has a cavity matching the boattail
angle and shoulder depth. Make sure that the bullet is short
enough so that the entire punch tip is well within the die
cavity before any pressure is created. If the punch walls are
not supported fully by the die, the punch will crack when
pressure is applied. Making too heavy a bullet for the length
of the PF-1 die cavity may break the external punch.

When installing the internal punch, make absolutely
sure that the internal ejection pin punch is held by the stop
pin (in -M or -S systmes) or retraction pin (in -H systems).
Otherwise the pin may fall out of the die hole and be col­lapsed by the end of the die when the ram goes down, roll­ing it like a pretzel inside the ram. Shape the bullet by care­fully raising the ram and pushing the nose end of the bullet
down into the die.

Do not try to close the tip smaller than the size of the
ejection pin! Never force jacket material up into the ejec­tion pin hole: doing so will concentrate force in such a small
area that it can crack the die.

The fifth die is the LEAD TIP FORMER (LT-1). It
uses an internal punch with a cavity that is shaped to match
the curve of the PF-1 point former. The tip of this cavity
can be sharp (spitzer), radiused (semi-spitzer), round, or flat.

With any given diameter of bullet, you can use the
same LT-1 die, and simply change the internal punch for
different kinds of lead tips. But you should not use the wrong
caliber LT-1 die: this can cause poor accuracy because the
bullet is not properly aligned in too large a die, and it is
sized down and distorted with too small a die.

Use only the lightest possible pressure to just reshape
the tip. If there isn't sufficient lead extending from the jacket
to fill the punch cavity, the tips will not form correctly or
may fall off (because the jacket walls may nearly touch be­neath the false lead tip, cutting off the "stem" that connects
the tip and core). Do not push too hard, or you will make a
ring in the jacket at the punch edge.