A
Profuse Powder Perusal
The
problem with blackpowder, and the "fake" blackpowder
substitutes, from a safety and a performance standpoint is largely
due to its porosity and resultant extremely fragile particle structure.
By being uncoated, porous, and easily broken up it is highly impact
sensitive. A few grains of blackpowder in a baggie hit with a hammer
in your garage can make that "memorable" for you.
The safety issue is clear. The porosity of the powder allows it
to suck moisture out of the air, and that is a field performance
issue true to the adage "keep your powder dry." The negative
qualities of combined impact sensitivity, self-sustaining ignition,
and moisture attracting heavy reside left by the filthy stuff combine
to make it problem-filled propellant.
The easy ignition offsets
some of the moisture suckage; as few readily propellants ignite
easier, it is still used in some military / industrial applications
today as few products displace it. What is more difficult to manage
is the corrosion guaranteed to start just as soon as you take your
fouling shot in your muzzleloader, as well as the impact issue and
the easy ignition (cook-off) propensity that only have to
happen once in your lifetime to be of great concern. The heavy fouling
left behind after each shot may cause barrel pressures to skyrocket
in subsequent shots without barrel cleaning. Not a major issue in
muzzleloaders designed to accommodate this, it is a a known problem
in marginal-barreled frontloaders that do not have this as a designed-in,
tested-in consideration.
Moving along to our
125 year-old variation of energetic Ping-Pong balls, there are powders
not suited to the Savage 10ML-II application. The same coatings
that make smokeless propellants inherently safe must be burned away
for proper ignition. You may have read references to the various
"thicknesses" or types of coatings in smokeless propellants--
but that is not really relevant to our ignition characteristics
in the Savage 10ML-II. It is the percentage of coatings in a given
powder by weight that can make them too hard to ignite for low-resistance
use (as in a low coefficient of friction sabot). This should
explain why "ball powder" is a poor choice for muzzleloading.
The small ball of powder is completely ensconced with coating, and
in relationship to its weight, is one of the highest percentage
of coating powders. Hopefully, this should explain why they may
have ignition problems in a muzzleloading application-there is just
too much coating to burn though without the direct resistance (shot
start pressure) of a gilding metal jacket bullet being forced
into rifling from a cartridge. The "shot start" pressure
in a .30-06 Springfield can easily exceed 10,000 PSI. We don't have
anywhere near that figure to work with in a load from the muzzle
application, and it looks like we never will. The severe limitation
of "loads from the muzzle" (we really want easily loads
from the muzzle) prohibits that. As a sidebar, most smokeless
propellants are assumed to be "progressively" burning
propellants. In a general sense, that is true that they continue
to produce gas as they travel down the bore. From a technical standpoint,
it is not true. In the case of ball powder, once the stabilizing
coating is burned and the powder is properly ignited, you have maximum
surface area producing gas. From that point on, the surface area
of ball powder diminishes, and the gas-producing ability shrinks.
Ball powder becomes a degressively burning propellant, producing
less and less gas as it travels down the barrel in concert with
its ever-decreasing surface area shrinkage.
Most extruded powders
have a "progressive curve" and a degressive curve. The
point of intersection of these curves are contingent somewhat on
ambient conditions and application. To address Savage 10ML-II powders,
the comparatively tough, position insensitive Accurate
Arms 5744 reigns supreme in terms of overall use for 200
to 300 grain projectiles. As a double-based powder, it is more flexible
than its single based counterparts in the Savage application.
For best performance,
single based powders must compliment the projectile weight (sabot
and bullet) for optimum performance. That indicates Vihtavouri
N110 for 250 grain bullets; Vihtavouri
N120 for 300 gr. class projectiles, and Accurate Arms 2015
for 350-400 grain projectiles. Assuming the same single base of
nitrated cellulose (more nitration of the cellulose means more
energy potential) as we go with the more heavily retarded slower
powders due to both geometry and coating percentage, their mainstream
usefulness becomes less and less. Using the same Savage 10ML-II
ignition system, our ability to properly ignite taller and taller
columns of more heavily retarded powders becomes a realistic field
use limitation, along with increased recoil, and a coinciding reduction
in useable barrel length.
This
monograph does not attempt to encompass all variables, but hopes
to touch upon the primary considerations for what we all want: loads
with supreme reliability that build supreme confidence.
©
July, 2005 by Randy Wakeman
