Bullet sizing is the process of
reducing the largest diameter of the bullet using a die and a press. Lyman
makes a lubrisizer and the dies and top punches, as do RCBS and others.
These presses reduce the largest diameter of the bullet, and
simultaneously allow filling the lube grooves.
When a bullet is sized in a lubrisizer
the smaller diameter sections are “bumped up” or made larger in diameter.
As an example I have a Lyman 311291 mold that casts bullets in wheel
weights with band diameter = largest diameter of .3115”/.3125” and nose
diameter of .299”/.301” just in front of the first band. I lube and size
these and seat gas checks in a Lyman 450 lubrisizer with minimum pressure
on the handle-I’m not trying to bump up the bullet at all. After
sizing/lubing/installing gas checks the bands measure .3118”/.3122” and
the nose measures .3008”/.3013” just in front of the first band. Before
sizing, the noses of these bullets will go into the muzzle of my 30/30
bench gun up to the forward band. After sizing, the bullet noses stop in
the muzzle about 3/16” from the forward band. The small difference in
dimension makes a big difference in bullet fit.
In the first Lyman Handbook of
Cast Bullets there’s an article by Frank Jury (pg 21) that starts off
by showing how sizing bullets to .310” resulted in dramatically smaller
groups than when the bullets were sized .309”. This led me to spend a lot
of money and time attempting to duplicate these results. I bought about
every 30 caliber sizing die that Lyman made, but I never found accuracy
varying much with .001” variations in diameter. (One thing I did find is
that sizing dies had typical tolerances. A .308” die might size bullets to
.3083”, a .309” die might size bullets to .3087”-both dies were within
tolerances but the difference between the two was .0004” rather than the
.001” that I expected. I believe that the tolerance on a nominal
308”sizing die is .3076”-.3085”)
I prefer not to size bullets, or size
them as little as possible. My experience is that the bigger the bullet
is, the better it shoots. I have Lyman 311299 molds that cast fairly round
.314” diameter bullets that shoot very well out of about any 30-caliber
gun I’ve tried them in. These shoot very well un-sized, as cast. Sized to
.312”, lubricated and with gas checks seated, these bullets shoot almost
as well as when shot as cast.
This big bullet premise works for most
calibers I’ve cast bullets for, from .22 to .45.
I do use the lubrisizer with oversize
sizing dies for seating gas checks and lubricating-not sizing (much)- some
A custom-made nose punch for a
lubrisizer can be made with a large nose punch and some epoxy-using the
bullet to mold the epoxy.
Some shooters recommend bullet
bumping, the process of squeezing a bullet in a sizing machine in a die
that is larger in diameter than the bullet as cast. Squeezing the bullet
shorter makes it larger in diameter, up to the size of the die. I’ve been
sizing and bumping bullets in my lubrisizer for years, and I’ve never got
better accuracy from a sized or bumped bullet than from a proper diameter
bullet as cast. What I have got is a Lyman 450 Lubri-sizer with the handle
all brazed up because I broke it bumping bullets up in some of those
oversize sizing dies.
When you buy a rifle and don’t have and
can’t find a bullet big enough, bumping a slightly smaller bullet up to
size may allow you to shoot the gun with reasonable accuracy until the
proper mold arrives. The same may apply to sizing a bullet down, but
shooting oversize bullets frequently works well.
I believe that sizing and bumping
bullets can and does work when using specially designed and built dies and
an appropriate press. John Ardito wrote about sizing and bumping bullets
to fit his rifles, and set many records. Shooters using his methods hold
many of the current records. In my opinion, only advanced cast bullet
shooters using expensive dies and equipment will benefit from this.
A legend that seems immortal says that sizing damages the accuracy
potential of a bullet, and more sizing damages it even worse. There are
all sorts of ‘evidence’ quoted as proof: Pope didn’t size his bullets, nor
do many Schuetzen marksmen, etc, etc. And that is perfectly true. But it
is also perfectly true that this legend got its start when sizing dies had
sharp shoulders, and would shear lead off of the sides of the bullets, not
swage them down uniformly like today’s dies do. And it was the usual case
that the bullet sides were not sheared uniformly, which would indeed
damage the accuracy potential of the bullet.
This is simply not true in my
experience with modern sizers that swage bullets instead of shearing them.
I have swaged bullets from an ‘as cast’ diameter of 0.460” (for a 45-70)
down to 0.445” (for an 11mm Mauser). In fact, Lyman once sold swaging dies
for this exact purpose. And accuracy was excellent!! I would be willing to
make a substantial wager that any ‘loss of accuracy ‘associated with
substantial sizing (diameter reduction) will be found due to worsening of
bullet fit in the throat of the rifle, not the diameter reduction per se.
If you doubt it, may I suggest that you put up your favorite target load
except that you use some bullets that were sized down from the next
caliber up. For example, size some 8mm bullets (similar weights) to 0.311”
or 0.312” (depending on what your rifle ‘likes’) and seat them into the
throat the same way as your normal load. I’d be surprised if you see much,
if any difference in grouping. )
How To Hone A
Oft times we find ourselves needing a
bit more girth in a bullet to please a particular firearm. And, as
sometimes happens the size we need isn't available or we don't want to pay
for the custom manufacture of one. You can do this yourself and accomplish
very accurate results for just a few cents worth of materials (not
counting the size die) and a bit of time.
What you will need:
1) A sizing die
that is as close as possible to what you want.
2) A length of
steel rod that is close to 3/4 of the diameter of the existing die, and
long enough to protrude at least 2" beyond both ends of the die.
3) Wet or dry
emery paper of 320, 400, and 600 grit. If you do need to remove more
than a couple of thousandths you should also include 220 grit. Actually
the 400 will finish the inside well enough, but hitting it with a bit of
600 sure slicks it up.
4) Oil. Most any
oil will do.
What you do:
The paper should be cut long enough to
extend out either end of the die, almost as long as the steel rod. Wrap
your starting coarsest grit paper around the steel rod a couple times and
apply some oil to the paper. Insert the covered rod through the size die.
With just your thumb and a
couple fingers on
each end of the rod, roll it up and down your thigh (while sitting)
applying only mild pressure. The reason for using a rod as large as
possible is to keep from tapering the inside of the die, by having a
slender rod bend under pressure. This will get your pants leg fairly well
oiled up, so use old pants. Or you can staple a bit of cloth to a length
of wood. Most any surface that the die can turn on is fine. I use a piece
of mud flap screwed to a bit of 2x4, and clamp it in the vise, and it's a
good working height.
Roll the steel rod occasionally as only
a small portion of the paper is in contact with the interior of the die.
You should also swap the die end for end every now and then to make sure
the metal removal is as even as possible. Remember the throat of the die
is tapered to admit the bullet and we're only wanting to open up the
actual sizing portion of the die.
When you check your work you don't need
to put the die back in the press. Just drill a hole in a board bigger than
the bullet and place the die over it. Place a bullet in the die and tap it
through. Remember to leave a bit of metal to remove for your polishing
down to final size with the finer grit paper. The first time I did this I
just took it down to where I wanted it without thinking of the finish. It
works, but you do need a bit more effort to get the bullet in and out, and
it just isn't the right way to do it!
Your existing plunger will still be
fine in the honed out size die, unless you opened it up several
thousandths. Even then it may still work fine, but you'll need to pay more
attention to the lube consistency and the amount of pressure you exert on
the lube reservoir.
How To Bump
Bullets In The Lubricator/Sizer
I have only used the Lyman 45 and
450 Lubricator/Sizers, but understand that the SAECO and RCBS machines
will also bump bullets.
The problem with bumping bullets in
a Lyman machine is that the handle, a flimsy proposition at best, will
The warning that Lyman handles are too flimsy for bumping, and will break
is correct in my experience also. But my remedy was to weld a reinforcing
strip of steel across the top of the handle above the pivot holes, which
is where the handles is thinnest, and the breaks occurred. These strips
were the same size and thickness as the original handles, and perhaps an
inch or an inch and a quarter long. Welding was completely across the
surface. This simple alteration has prevented further problems for several
Here's my Lyman 450. Note the
repair/braze area where the handle broke-several times.
The ADJUSTING SCREW adjusts how far
down the bullet can be pushed in the sizing die by the TOP PUNCH. Note
that the TOP PUNCH fits into the sizing die and into the NUT.
I use the NUT; it fits inside the
SIZING DIE LOCK NUT; to stop the downward motion of the ram and TOP PUNCH.
Then I adjust the ADJUSTING SCREW to limit the downward movement of the
bullet in the sizing die. When the bullet is all the way down, and there's
space between the ram and NUT, further pressure on the handle mashes the
bullet shorter and bigger in diameter. Other and better arrangements are
made by those more mechanically inclined than I.
The example is the Lyman 311299 bullet,
with a bore-riding nose that should be about .300", and a set of three
bands over .308" in diameter. I'm assuming here a 30-caliber barrel of
.300" bore and .308" groove.
My 311299 molds produce bullets with
varying nose diameters and bands over .312" that are sized .312" in a
In the process of sizing and lubing the
bullets, with no undue pressure on the handle of the 450, bullet noses
increase one thousandth of an inch minimum. They get bumped up. By
fiddling with the lubricator/sizer and increasing the pressure on the
handle, it is easy to increase the nose diameter of the bullet by three to
four thousandths of an inch. Somewhere around four thousandths of an inch
the nose starts to bend into a banana shape, and/or the handle of the
With bullets under .312" band diameter,
sizing normally, without undue pressure on the handle increases band
diameter at least one thousandth of an inch. All my 30 caliber molds make
bullets that have the base bands "shined up" in the lubricator/sizer.
This Lyman 319289 bullet has bands of
constant diameter. Let's assume that the bullet is .321" in diameter, and
we want it larger. Run it through a .323" sizing die, and make sure that
all the lube grooves are filled. Then set the lubricator/sizer and force
the handle down to expand the bullet to sizer diameter, .323". Again,
three to four thousandths of an inch is the maximum increase in diameter
before the nose gets to looking funny or the handle breaks.
I have bumped many bullets using
conventional sizing dies in the Lyman 450, calibers from 22 to 45, and
never increased accuracy. Others have had great success.
I like the Lyman 311299 and 314299
bullets, and have worked with them a lot. Here's a picture of the 311299,
the 314299 looks exactly the same. This story is about the 314299. I have
been working with a Winchester M54 rifle in 30/30, casting bullets in 25:1
lead: tin and linotype. The nose of the bullets measure .3032"-.3036", and
cast in either of the alloys the nose is lightly engraved when the
cartridge is chambered. With 25:1 and bullets sized .312", a cartridge
overall length of 2.895" chambers in the gun, mashing that front band into
the throat. With linotype and bullets sized .312", that front band stops
the cartridge from chambering at an overall length greater than 2.865"-it
won't be mashed in. So I sized bullets of both alloys down to .309" in
search of a longer overall length for the linotype bullet, and for
accuracy in general. The linotype bullets easily chambered at 2.895"
overall length, but the 25:1 cartridges had the bullets pushed way back
into the cases when I attempted to chamber a couple.
Now, after sizing to .312", the bullet
noses grew from .3032"-.3036" to .3040"-.3045". But, after sizing to
.309", the 25:1 soft bullet noses had bumped up to .306"-.3092", the
bullet jammed in the rifling when chambered and was pushed back into the
cartridge case. The linotype bullet noses were still about .305" and
chambered with no problem.
I'm telling this story to illustrate
the notion that sizing bullets can change dimensions of the nose enough to
affect how the bullet fits in the gun, and the maximum overall length. And
that alloys of different hardness are affected differently by sizing and
bumping, and that hardness affects how easily the bullet is engraved by
the rifling. Change the sizing diameter and other things change.
I seated bullets of both alloys to
2.875" and crimped the case necks slightly to keep the bullets from being
pushed into the cases, loaded them up and shot five 5 shot groups with
each yesterday, 4/18/07. The 25:1 bullets averaged 1.32" groups at 100
yards, the linotype bullets averaged 1.1".