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BARREL BREAK-IN PROCESS
By Wayne McLerran
Posted: 5/31/15

When breaking in a barrel the goal is to burnish (smooth out), down to
the microscopic level if possible, any chamber reamer marks in the
throat or rough edges in the lands and grooves from the broach cutting
process.  A smoother throat and bore is less likely to lead.  But barrel
break-in is somewhat of a controversial subject.  Most if not all rifle and
barrel manufacturers publically recommend it but some manufacturers
will privately admit it may not be necessary, especially for barrels with
lapped (polished) bores.  I’ve discussed the subject with several barrel
producers and distinctly remember one such discussion a few years ago
with the owner of a high-end cut-rifled barrel manufacturer.  Since the
bores were lapped after the riflings were cut he was not convinced
breaking-in his barrels was necessary.  But rather than spend time
discussing and debating the subject at length with numerous customers,
it was more expedient to “side step” the issue and post a procedure on
their website since most of his customers were convinced that a break-
in process was necessary.

While buying and selling scores of Browning and Winchester BPCR, many
customers requested recommendations on a barrel break-in process.  
Since the rifles feature Badger cut-rifled barrels, my standard response
was to refer them to Badger’s website for their step-by-step
instructions.  Since Badger Barrels is no longer in business their
procedure is listed below.  I’ve also included a much simpler approach
developed by Lee Shaver that I will be using from now on.

By the way, breaking in a barrel does not just apply to a new rifle.  A
used rifle can also benefit from the process, especially if the bore was
never properly cleaned between shooting sessions and was fouled from
the beginning with copper and/or lead and carbon residue.  With a used
rifle it’s very important to ensure the bore is absolutely clean prior to
starting the break-in process or it will be a waste of time.  Here’s where
Lee Shaver’s break-in technique “shines”.  It not only saves a lot of time
and effort, but very effectively removes all fouling during the simple and
short break-in procedure.

Badger Barrel’s Break-In Procedure

Break In with Jacketed Bullets:
For the first ten shots we recommend, if possible, using jacketed bullets
with a nitro (smokeless) powder load.  Clean the oil out of the barrel
before each shot using something as simple as Windex™ which will soak
the oil out of the pores.  After firing each bullet use a good copper
cleaner (one with ammonia) to remove the copper fouling from the
barrel.  We do not recommend anything with an abrasive in it since you
are trying to seal the barrel, not keep it agitated.

After cleaning with bore cleaner, clean with Windex after each shot.  
Use Windex because many bore cleaners use a petroleum base which you
want to remove before firing the next shot.  This will keep the carbon
from building up in the barrel (oil left in the pores, when burned, turns
to carbon).

To keep the temperature cool in the barrel, wait at least 5 minutes
between break-in shots.  The barrel must remain cool during the break-
in procedure.  If the barrel is allowed to heat up during the break-in, it
will destroy the steel's ability to develop a home registration point, or
memory.  It will have a tendency to make the barrel “walk" when it
heats up in the future.  I am sure we all have seen barrels that, as they
heat up, start to shoot high and then "walk" when it heats up.  This was
caused by improperly breaking in the barrel (generally by sitting at a
bench rest and shooting 20 rounds in 5 minutes or so).  Then, for the
rest of the gun's life the man complains that the barrel is no good.  If
you take a little time in the beginning and do it right, you will be much
more pleased with the barrel in the future.

If you look into the end of the barrel after firing a shot, you will see a
light copper-colored wash in the barrel.  Remove this before firing the
next shot.  Somewhere in the procedure, around shot 6 or 7, it will be
obvious that the copper color is no longer appearing in the barrel.  
Continue cleaning between each shot with Windex and an ammonia-
based cleaner through shot 10.

If you have any ammunition left, you then may shoot 2 rounds and clean
it for the next 10 shots.  This is simply insuring that the burnishing
process has been completed.

In theory you are closing the pores of the barrel metal which have been
opened and exposed through the culling and hand lapping procedures.

Break In with Lead Bullets:
The same shooting/cleaning break-in process may be used when firing
lead bullets and black powder with the following exception: shoot 2
bullets, than clean and repeat the process after the barrel has cooled.  
Naturally, you must use a cleaner appropriate for removing lead and
black powder fouling.  You can also use harder lead bullets if available
to accelerate the break in.  This will accomplish the same as the
jacketed bullets but it will take 80 to 100 rounds to break in the barrel
with lead bullets.  That is why we recommend using jacketed bullets
when possible.

After this procedure, your barrel’s interior surface will be sealed and
should shoot cleaner and develop less fouling for the rest of its shooting
life.

Lee Shaver’s Break-in Procedure

Having used the jacketed bullet/clean-between-shot process in the past
and specifically Badger’s procedure when breaking-in one of my
Browning BPCRs, I was not looking forward to repeating the very lengthy
process with my other Browning’s.  Fortunately Lee Shaver came to the
rescue with his much simpler and less time consuming process.  With
permission from Lee I’ve included the details of his procedure.  It’s from
a larger article Lee published in the May 2013 edition of The Single Shot
Exchange Magazine.

Excerpt from “Breaking In a Barrel” by Lee Shaver:
Several years ago, I developed a process for breaking-in barrels for lead
bullet use that eliminated the afternoon of shooting and cleaning with
jacketed bullet.  It
began because I would occasionally have to get bad
leading out of a barrel for a customer, and when you charge what a
gunsmith must charge to stay in business you don’t want to spend an
afternoon scrubbing the lead out of a customer’s gun.  And I’m sure the
customer would rather not pay for said services.

What I learned was that when scrubbing lead out of a barrel, I could run
a tight oily patch through a few times and then take the patch off the
jag.  I would then unroll a little 0000 steel wool and cut a piece the size
of the patch.  Place that over the patch and then run it all through
together.  (The proper fit is when you have to bump the rod a few times
with the palm of your hand to get it started in the bore.)  When you
shove that steel wool over a patch through the bore of a badly leaded
barrel, it may sound like paper tearing as the lead is ripped out of the
barrel in a pass or two.  I can clean the lead out of the worst barrel in
about ten or fifteen minutes that way, and an average leaded barrel will
be clean in a few strokes.

After using this technique for a while, I began to notice that the rifles
that I was de-leading that way seemed to lead less afterwards, which
got me to thinking.  We use fine steel wool on the outside of old guns all
the time to do some cleaning or spot rust removal, and it does not
damage the surface of the steel.  It just scrubs it.  Which lead me to
consider the fact that we are trying to break in a barrel by smoothing
the surface without cutting, and it seems to me that process would go
much quicker if we used something on the inside of the bore that was
closer to the hardness of the barrel instead of lead or copper.  So I
started trying the steel wool and oiled patch technique on new barrels
before shooting them.  I use it about as tight as I can get in the bore and
wear out a steel wool pad or two in about 15 minutes, then I go and
shoot the rifle.

How well does it work you might ask?  On a few occasions, I have built a
new rifle and taken it to a match without ever having fired the rifle.  All
have performed flawlessly in their first match and several times I won
the match or set a record with them.  On one occasion, I set a new 300
yard range record with the first 13 shots out of a barrel.  This method
has become a service we offer to our customers here in the shop and I
have shared the technique many times with others.

So the next time you get ready to shoot that new rifle, just remember it
is important to break in a barrel properly, but if the operation you are
doing to the barrel cuts – it is not breaking it in.  It may be making the
barrel smoother, but to break the barrel in you need to polish the bore
by burnishing not cutting either by shooting it or scrubbing it.
Lee Shaver

Wishing you great shooting,
Wayne