TexasMac's Web Site
By Wayne McLerran
Posted 10/8/19

When I started competing in local BPCR silhouette in mid-2012 I used a
blow tube but struggled with bore fouling issues, most likely due to
inconsistent or insufficient blowing technique.  Attempting to deal
with the temperature changes from match-to-match in Central Texas
was a struggle, especially during the summer.  Based on
recommendations from several experienced shooters at the time I
switched to bore wiping, first starting with RV antifreeze solution,
then “moosemilk” (Murphy Oil Soap and water), and eventually to a
solution of Napa brand water-soluble oil and water.  The water
removes the fouling and the soluble oil lubricates the bore for the
next shot.

Things were going well and after 3 years of competitive shooting I
eventually moved up to AAA classification.  Another year passes while
attending 15 matches with mostly AAA scores.  Feeling pretty good
about my shooting ability I signed up for the annual Texas State
Match.  After the first day of the 2-day 40-shot-per-day match I was in
2nd place with a 29 and figured I had a real chance at winning the
scope category.  The next day was when disaster struck and bore
leading reared its ugly head.  I couldn’t hit anything consistently
including the pigs and ended up with a score of 19 and a total of 48
for the match, which placed me in the middle of the pack.  To say I
was disappointed was an understatement.

After returning home and using a bore scope the problem was evident
– lots and lots of leading which started a couple of inches in front of
the chamber to about ¾ of the way down the bore.  When cleaning
the bore with very tight patches soaked in turpentine the patches
came out with long strips of lead.  I was using 16:1 alloy 398gr bullets
(BACO JIM409400M5) lubed with White Lightning over 69grs of 1.5Fg
Swiss and a 0.060” fiber wad.  The load resulted in a velocity of
1330fps.  Due to the combination of the extended freebore in the
throat and the tapered bullet driving bands, the compression was only
0.010” with the driving band contacting the leade.  This is a relatively
“hot” load but after a year of shooting the same loads this was the
first indication of leading.  Scratching my head as to what was going
on I spent some time attempting to figure out what changed while
researching the possible causes of bore leading.

I considered the most common causes including the bullet diameter
being too small, allowing hot gasses to blow by, i.e. gas cutting prior
to the bullet bumping up (obturating) to fill the chamber and throat.  
Another is the alloy could be too hard preventing the bullet from
obturating sufficiently or quickly enough.  Other possibilities include
inadequate lube or the cartridge overall length was too short (bullet
seated too deep) allowing blow by.  And, since the nose of a bore
riding bullet is not lubed, it can leave behind lead when it obturates to
fill the grooves, especially if the bore is dry.  But none of the above
made sense when considering past successful shooting results with the
same bullet cast from the same alloy, with the same lube and
reloaded the same.  And the cartridge is certainly not too short since
the 1st driving contacted the leade.  Plus, I wipe between shots which
would compensate to some extent for inadequate lube.

Several more matches followed the Texas State Match including a trip
to the NRA Whittington Center BPCR Nationals with mediocre to poor
scores as I struggled to figure out the cause of the leading.  I even
changed bullets and reduced the velocity but the leading persisted.  
Nothing was obvious until I overheard a discussion between two
shooters.  One guy mentioned that if the wiping patches left too much
solution in the bore, leading would result.  The comment struck a
chord.  Prior to the 2nd day of the Texas State Match, after soaking
the wiping patches in a solution of soluble oil and water, I’d been
squeezing them out until most of the liquid was removed, leaving the
patches lightly damp.  When preparing for the 2nd day of the match I’
d decided to leave the patches wetter to better clean and lube the
bore, and continued to use them in the same condition for subsequent

They were wet enough that some of the solution would leak into the
action when inserting the patch into the chamber.  Following the
overheard conversation the patches were squeezed out good but left
damp for the next match.  That did the trick; there were no signs of
leading with the exception of a few tiny flakes.  Since then I’ve shot in
many matches with the same outcome.  Who would have thought…?  
Too dry of a wiping patch can result in poor accuracy due to burnt
powder and lube fouling remaining in the bore.  Apparently too wet
will have similar results due to leading, another form of bore fouling.

By the way, after solving the leading problem, I’ve been experiencing
vertical stringing on the turkeys and rams.  During another discussion
between match relays a very experienced shooter mentioned that too
much soluble oil in the wiping solution can result in vertical stringing.  
He recommended no less than a 7:1 (water to oil) mix.  I had recently
increased the oil concentration from 10:1 to a 5:1 mix, figuring the
additional oil would do a better job of lubricating the bore in the very
hot Central Texas heat, which was a mistake.  So now I have another
variable to experiment with and possible “fodder” for a future
article.  Nothing comes easy in this sport, inviting lots of
experimenting, which is one reason I enjoy the challenge of reloading
as much as the shooting.

Wishing you great shooting,