From: "Alex Hamilton", [EMAIL PROTECTED]
Many interesting comments have been made regarding Vihtavuori powders
but no
real explanation has yet been forthcoming of why I experienced ferocious
leading with N310 powder but not with Hercules Bullseye - all other
components in the equation being the same. Whatever the mechanism that
is
causing the leading, it must be associated with the powder as nothing
else
has been changed. There was no velocity leading in the barrel. The
leading
occurred solely in the cylinder chamber throats (the portion ahead of
the
chambered cartidge) and was fairly uniformly distributed round the
chamber
mouths in all six chambers.
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The leading in the cylinder exit holes is caused by gas cutting and my
Python also suffered from it badly.
I do not believe it has much to do with the powder you use, but it may
be affected by by the rate at which the powder burns, because that
affect how the bullet sets up on firing.
Andrew Lambley has explained that there is not sufficient time for the
transfer of heat to take place and cause the leading to the extent that
you describe.
I have even carried out an experiment to prove that melting of the
bullet bases is not the cause of leading.
I cut ordinary polystyrene as used in parckaging into " strips and then
used a case with suitably sharpened mounth to cut wads, which I placed
immediately below the bullet. Recovered wad were hardly singed and
could be used again, but they did not reduce the leading one bit.
The bullet was Lyman 358212, 148gr Round Nose, which I used for 20 years
in 9mm Parabellum pistol without any leading and that would indicate
that the cause is the size of the cylinder exit holes and not the
powder. Furthermore, I used the same charge of powder, 2.6grs, with
Hollow Base Wadcuter home swaged from pure lead wire. These bullets
were really soft and they were subjected to higher pressure/temperature
because seating them flush with case mounths meant that there was far
less air space above the powder than with 358212. But, being soft,
HBWCs obturated the exit holes and there was no leading anywhere.
If you are not casting bullets you are not in a position to vary the
hardness of the alloy and probably not even the size of the bullet if
you are using only commercially cast bullets. You say that the bullets
you use are sliding fit. Well, if they are more than 0.0005" smaller
than the exit holes and hard cast you will most probably get leading.
Ideally, you should try bullets which are 0.0005" larger than the exit
holes and those you cannot push through by hand, not easily anyway.
You also mention "velocity leading". This is caused by the bullet
lubricant breaking down as the velocity and temperature increase. The
build up of leading starts at the muzzle, where the velocity is highest
and spreads towards the breach, but usually stops some way down from the
muzzle. Someone once wrote in jest that if you cut off the leaded part
of the barrel you would solve the problem as the bullet would then leave
the shortened barrel before the velocity reached the stage where the
lubricant failed. This would, of course, also reduce the muzzle
velocity, so the solution is to either reduce powder charge or change
bullet lubricant for one better suited to higher velocities. Unless you
are very careless, you are unlikely to see this phenomenon in pistols,
but it is not uncommon in rifles. But the accuracy will go long before
this stage is reached and having learned how to avoid it, I have no
personal experience with this type of leading.
In the days when we had pistols I knew many people that used Vihatvouri
N310 in revolvers without any problem and that suggest to me that is
your revolver that is the cause of leading and not the powder,
notwithstanding that the problem may not be there with some other
powders, but there we are comparing apples and oranges.
Alex
Cybershooters website: http://www.cybershooters.org
List admin: [EMAIL PROTECTED]
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