Deposits of bullet alloy that have
been smeared into the surface of the gun's bore. In extreme cases, it will build
to the point where the rifling is completely choked with deposits and the barrel
appears to be smooth-bored. Once leading begins, it will have a tendency to
strip alloy from the next bullet which builds the deposit with the next shot.
Each successive bullet fired will "iron" the lead into the surface of the bore
and make it more difficult to remove the deposit.
Forcing Cone Leading
This is normally
caused by shooting a bullet that is too hard (BHN too high) for the velocities
used. Either use a softer alloy, or increase the charge (within published
loading data, of course!) to correct this problem. This can also be caused by
shooting a bullet that is too small in diameter. Revolvers will lead in the
chamber and forcing cone while closed breech weapons will lead in the chamber
and the beginning of the rifling area. Have the cylinders measured for revolvers
and size the bullets to them, not the bore (unless the bore is larger than the
chambers, in which case the problem will have to be corrected by a gunsmith or
the factory) and measure the bore in closed breech weapons to determine proper
bullet diameter. Rule of thumb says the bullet should be .001" larger than the
bore or equal to (or very slightly larger than) cylinder diameter in a revolver.
If the alloy is soft enough, you can get away with a slight "push fit" in a
revolver cylinder, but certainly the bullet should be large enough to not fall
through the small diameter portion of the cylinder freely!
This is lead fouling
that begins in the rifled portion of the bore, but after the chamber or forcing
cone, and extends into the bore for a distance of up to several inches. This is
normally caused by shooting a bullet that has a low BHN (too soft) for the
pressures or velocities used. The bullet will actually strip as it enters the
rifling as it does not have the strength to properly engage and begin rotation
due to the forces pushing it through the barrel. It doesn't mean it's a bad
bullet alloy, it just means you are driving it too hard. If you want to go
faster, you will need a stronger alloy with a higher BHN number. Alloys must be
used which fit the application. There is no such thing as a "magic" alloy that
works for every single application!
When lead fouling occurs at the muzzle end, you
have run out of bullet lubricant. Either use a better lube, or more of it to
correct the problem. If you can, use a bullet with more, or deeper and/or wider
lube grooves. After firing a box of cast bullets, say 20 to 50 rounds, there
could be a lube "star" on the muzzle. This indicates that there is simply left
over lubricant and the bullet exited the muzzle with plenty of lube. If,
however, you find a lead "star" instead you need to try something different as
the bullet ran out of lube. You may be able to simply reduce the charge (lower
velocity) and correct this. The alternatives are use a better lube or a
different bullet design that can carry more lube. As an example, there are
.45-70 Govt. 405 grain bullets on the market with only a single lube groove.
Barrels over 16"-18" long using this single lube groove design bullet will
exhibit muzzle leading after only a few shots! Frankly, the only reason this
bullet exists is that it is simple to manufacture!
Normally, this is
caused by shooting a bullet that is too small in diameter for the
bore. If the bullet doesn't seal the bore, gas will be able to escape past
the bullet causing a cutting action similar to the way a cutting torch
cuts steel. By the way, gas cutting will only occur if gas can flow. If it
flows, what you have in effect is leak. The bullet is not sealing the
propellant will not melt the base of a
lead bullet! There is simply too much physical mass to heat to the melting
point of lead (about 600-700F) in the short time a bullet is exposed to
the propellant gas to bring it to it's melting point! If you want proof,
examine wads used in shotguns or black powder cartridge loads after
firing. They may show slight darkening, but won't be consumed in flames
either! If the burning powder won't melt the plastic or burn up the
cardboard, why would it melt a bullet base? The answer is, it can't.
Some years ago
my Dad and I ran tests to see if heat could actually melt the bullet
bases. We used .357 and .44 Magnums as the test vehicles. To the bullet
bases we glued flash paper, the kind magicians use. No matter which powder
we used, we were never able to ignite the flash paper. We also put low
temperature wax on the bases of the bullets and again were unable to get
any wax to melt. As was said already, if you can't melt the wax you sure
won't melt lead.
bases are caused from other things, principally incorrect bullet fit to
the bore or a bad bullet to begin with!
bullet accuracy is directly related to the pressure levels your cartridge
is loaded to. If the operating pressure is too low relative to the
bullet's BHN (hardness), you will not achieve obturation and the bore will
not seal. This will cause gas leakage and erosion (gas cutting) that
causes leading at low pressure and low velocity! Optimum accuracy occurs
at a point just below the pressure levels that induce breech leading for a
given bullet alloy. In other words, if you are shooting an excessively
hard bullet for Cowboy Action pressure levels, you will get leading,
usually in the forcing cone or chamber area.
Use a bullet of
proper alloy for the velocity you are shooting. Many shooters today are
using bullets much harder than is called for. In addition use the best
lubrication you can get. These three things, proper fit to the bore, proper
hardness for the velocity/pressure, and proper lube can make shooting cast
bullets an enjoyable time instead of a headache.
of the above information was originally published on the old Mid-Kansas
Cast Bullet website. Unfortunately they are no longer in business.
There are a number of good cast bullet providers available if you do not
cast your own. Those that I personally know are:
MONTANA BULLET WORKS
BEAR TOOTH BULLETS. There are many others also, but I know these people.