By Wayne McLerran
TexasMac's Web Site

After rendering 360 lbs of lead consisting of 60 lb ingots into 1 lb ingots, a cast
iron pot was left with a thin layer of lead at the bottom that could not be removed
with a sharp scraper or steel wool.  Over the years I had run across many threads
suggesting that a 50/50 mix of hydrogen peroxide and vinegar, common solutions
found in most households, would easily remove lead from firearm bores.  I had
used the solution with success in the past, leaving it in the bore for an hour or so.  
But additional research on the subject found that the mix results in paracetic acid, a
corrosive agent known to etch iron and steel in strong concentrations.  So I
wondered what affect a weak concentration has on firearm bores?  Now I had the
ideal test sample for a lead cleaning test using the solution.  I took it a step further
as detailed below.

After scraping the heavier layers of lead and crud out of the bottom of the pot, it
was scrubbed with steel wool.  A splotchy thin layer of lead remained, filling the
pores and covering most of the bottom.  Next, a pint of 3% hydrogen peroxide and
a pint of 5% acidic vinegar were poured in.  The solution started to fizz very
slightly and within a few minutes began turning red.  In about an hour
approximately 75% of the lead was gone and the solution seemed to have stopped
working.  The old, now deeply, rust red solution was dumped out, the residue was
wiped out of the bottom of the pot and a fresh solution of equal parts hydrogen
peroxide and vinegar was added.  As before, the solution started to turn rust red
and within 15 minutes all the remaining lead was gone.

Based on the results it was clear the paracetic acid not only dissolved the lead but
oxidized the surface layer of the iron, turning it into iron oxide (rust), hence the
deep rust red coloration of the solution.  It was also clear that, based on the
strength of the ingredients the acid only lasted so long as it was used up in the
process of dissolving the lead and creating iron oxide.  Since the solution was
clearly etching the iron the next step was to figure out some way to quantify the
rate of etching.

So a hunk of clean #0 steel wool was placed in a glass jar and covered it with the
solution.  The wool was pressed down to remove most of the air and it settled to
the bottom.  The steel wool plus solution immediately began to turn red and fizz
(generate bubbles/gas).  After an hr the solution seemed to have stopped working.  
The steel wool was removed, cleaned under hot water and inspected.  The strands
were now much finer, closer to #0000 steel wool.

At the same time the steel wool was immersed a short piece of iron flat stock was
buffed with a wire wheel and inserted it in a glass jar.  The jar was partly filled
with the solution which slowly started to turn pink then to red.  The photos below
are the before and after results of the solution on the iron flat stock after 1 hr.  
Although the lighting is not the same for both photos and the difference in the two
surfaces could not be felt by rubbing a finger over them, it’s visually clear the iron
surface was etched.

Later, after receiving comments that leaving the solution in the bore for 5 to 10
minutes does not damage the bore, another test was in order.  Using the same, now
very clean, piece of iron flat stock, it was heated it up with a torch, wetted it with
flux to remove any oxides and a few globs of lead/tin solder melted on it.  Most of
the solder did not adhere but a sufficient amount for the test remained.  After
scraping off the heavier solder, the remaining very thin layer of splotchy lead was
sufficient.  The lead coated iron was immersed in the hydrogen peroxide/vinegar
solution and the clock started.  Progress was checked at 10 minute intervals and I
could not detect any fizzing.  The solution turned a light grey in about 10 minutes.  
By 20 minutes it was light pink. By the time the lead was removed (about 1 hr), the
solution was deep rust red.

Conclusion/Comments: Significantly longer than 5 to 10 minutes is required to
remove even a thin layer of lead.  If the solution is only in the bore 10 minutes or
so, minimum etching will result.  But if the solution is used to clean the same bore
6 times the accumulated bore exposure to the solution is 1 hr.  At this point the
testing was stopped and the case was closed as far as I was concerned.

The bottom line is a solution of hydrogen peroxide and vinegar will never again be
used in my firearms to remove lead.  Although some contributors to various
Internet forum threads on the subject suggest it's OK to use the solution for a few
minutes and other report allowing it to soak in the bore overnight, based on my
findings even short term use will most definitely etch the bore to some degree.

Wishing you great shooting,