An email response I received from Lyman on leading

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warnerwh

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I'm not very knowledgeable about using cast bullets. After reading quite a bit of information on leading I was still unsure so I wrote to Lyman. Here is their response to my questions:

"There really is not a set velocity limit for a given type of alloy. It is a
combination of velocity and pressure that will determine which alloy is best
in a given load. Other factors such as barrel condition, groove diameter vs
bullet diameter, and lube used will also all factor in."

They don't give a lot of credence to the velocity and hardness knowledge I have been reading in regards to leading. It's velocity and pressure that determines which bullet to use and not bullet hardness, at least that's how I read it. Maybe I am not understanding what they are trying to say.
 
It sounds to me that what Lyman is trying to say is that they want to be polite and answer your questions, but not say anything substantive for which they might be liable.

Clearly, you need to read more corporate-speak, warnerwh.

OTOH, since we have not seen the question(s) you asked, perhaps they answered what you asked...post a copy of your questions!

Jim H.

added on edit: Since posting this, I have moved on down the line and read the other discussion for which the questions were sent to Lyman. But, I'd still like to see just what the question was. (The Old English Teacher just can't let go....)
 
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Here is what I asked Lyman:

Greetings: There seems to be some confusion on what the ideal
> hardness of a cast bullet would be for various velocities. It has been
> noted that you list loading data using linotype alloy for various rounds
> and velocities. If you could clear up under what circumstances/velocities
> a certain hardness bullet should be it will be appreciated. I will be
> posting your reponse in forum if it is ok with you.
 
Lots of different things cause leading

I will pass along my experience with leading.
After a 20 year hiatus I have once again began reloading.
The cartridge that was giving me problems was 9mm.
The bullet used was a 124 TC cast from wheel weights with
some tin added. The problem was the powder I was using.
Accurate # 2 it is just too fast burning of a powder for
a higher pressure cartridge like the 9mm. Once I started
using slower burning powders like AA#5, AA#7 My leading
problems have ceased to be an issue. Now days I am
reloading 357 sig cartridge with no leading issues, here is
a good link to learn about shooting lead.
http://www.lasc.us/CastBulletNotes.htm
 
Leading can be caused by many variables, including alloy hardness - either too soft, or too hard for the pressure of the given load. Other factors that can contribute to leading are bullet diameter, lube failure, and bore condition.

Most people try to compensate for leading by going to a harder bullet, which may or may not have a positive effect on the situation. Bullet manufacturers cast harder-than-woodpecker-lips bullets because they resist deformation during handling and shipping, and also because they have convinced most reloaders that rock-hard bullets are what they need. They use hard, crayon-like bullet lube because it doesn't fall out of the lube grooves during shipping, and doesn't melt unless it gets very hot.

Here is a link to a number of excellent articles on cast bullets: http://www.lasc.us/CastBulletNotes.htm Glen Fryxell shares Lyman's convictions on pressures and alloys.
 
a lot of leading problems are a result of gas blow by, i would look at the bullet to bore fit. sometimes you can go to a tighter bullet and leading stops, are at least reduced to a reasonable amount. also try a hollow base bullet. with a hollow base you can get away with softer bullets because you want the base to expand to bore diameter.
 
Undersized bullets, unless they have enough pressure to bump up and fill the bore, will cause gas cutting and leading when the hot, high velocity gases "cut" lead off the bullet on its way between the bullet and the throat and/or barrel. Leading will be mostly at the throats and forcing cone, but will continue until it fills the whole barrel if you keep shooting the offending load.

Properly sized bullets (in the range of .001 to .002 over throat diameter) will not suffer from gas cutting unless they are too hard.

Bullets that are too hard will not bump up and seal the throats and barrel well, even when sized properly, causing leading.

Bullets that are too soft to hold the rifling at the velocity they are driven at, will break loose from the rifling and "skid", breaking the seal and causing leading galore all the way down the bore.

If the bullets are sized properly, you can get away with them being a little harder than needed.

If the bullets are soft enough to bump up easily with the pressure used, you can often get away with them being a hair undersized, as long as they are hard enough to hold the rifling for the trip down the bore.

Hmm....did I miss anything? Probably. :)

Oh yea. Bullets that do not have enough, or good enough, lube, will tend to lead towards the end of the barrel.
 
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