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By Wayne McLerran
Posted 11/26/18

This article is about a couple of bullets I designed for use in the
Browning 1885 High Wall .40-65 BPCR.  Both of the single-cavity
moulds are available from Buffalo Arms Co. (BACO).  The JIM410410M3
mould/bullet, hereon referred to as the M3 bullet, was previously
described in detail in the following article:
Bullet Design & Loading
Considerations for the Browning .40-65 BPCR
.  The one distinguishing
feature between the M3 bullet and the newer design M1 bullet
discussed below is the diameter of the nose driving band.  The M3 nose
driving band is the same diameter as the nose whereas the M1 nose
driving band is 0.010” larger than the nose diameter.  So at this point
you’re likely wondering why the two different designs?

The M3 bullet was configured to load with a good bit of powder,
significantly more than the typical 55 to 62 grains or so used by many .
40-65 silhouette shooters.  Since the Browning has an extended throat
with approximately 0.190” of effective freebore, the bullet, sans nose
driving band, must be seated well out of the case in order to contact
the leade.  Therefore, unless it’s loaded short (off the leade) or
additional wad material is used to fill the case capacity, around 65grs
of Swiss 1.5Fg will be required to fill a fire-formed Remington case
when using a 0.060” wad and only 0.020” compression, resulting in an
overall cartridge length of around 3.2”.  Using the same wad thickness
and powder compression with Winchester or Starline cases will require
slightly more or less powder respectively.  By the way, I have shot the
M3 bullet with up to 68 grs of Swiss 1.5Fg and 0.120” of compression
with good accuracy.

Desiring a milder load with low powder compression, I requested that
BACO make one modification to the M3 mould, increase the diameter
of the 0.100” long nose driving band from 0.400” to 0.410”; the same
diameter as the other driving bands.  Increasing the nose band
diameter results in seating the bullet back into the case approximately
0.150”, reducing the powder charge by 5 to 6 grains with a 0.060”
wad and light compression, which Swiss prefers based on my testing
and as reported by others.  BACO agreed to make the change and
decided to add the mould to their listing as JIM410410M1.  By the way,
I had a good laugh
when I read their description of the mould, which
included the comment “Designed by Wayne McLerran, he made us
make this mould for him”.
With the two bullets pictured side-by-side, the obvious difference is
the increase in diameter of the 1st driving band of the M1 Bullet.  And
the M1 lube grooves appear to be slightly longer which they are but
not a significant amount.  The larger nose band adds slightly to the
weight, which is reduced to some extent by the wider grooves,
resulting in 410.3 grs versus 410.0 grs for the M3 bullet when cast
with 20:1 alloy.  Using 16:1 alloy reduces the weight of both versions
by approximately 2.5 grains.  I recommend 16:1 alloy with “Money
Bullet” designs to minimize the possibility of nose slump or setback.  If
the alloy is too soft the nose may slump back along the axis of the
bullet, resulting in possible bore leading, especially in a dry bore since
the nose is not lubed.  Nose slumping will also decrease the ballistic
coefficient, resulting in lower velocities and possible instability,
especially at longer distances.  The slightly larger nose driving band
also decreases the ballistic coefficient slightly but not enough to be a

I’ve found the M1 bullet shots best in my Browning with 59 to 62 grs
of Swiss 1.5F, resulting in approximately 0.020” to 0.090”of
compression with a 0.060” wad.  Due to the factory chamber and
throat design I do recommend using a 0.410” diameter bullet in the
Browning.  As to which bullet, the M3 or M1, is more accurate, it will
depend on your rifle and load configuration.

Wishing you great shooting,