Lymann manual: Lead hardness contra conventional wisdom?


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Quoheleth
January 24, 2010, 06:21 PM
Question for you folks...for lower pressure and slower velocity, softer lead bullets are the key, right? Thus, .38 Special 148gr wadcutter gets 12 BHN, but a full(er) house .357 magnum needs a 18+ BHN.

I recently picked up the Lymann Pistol and Revolver manual from my local gun shop, specifically because they had a whole slough of .41 load data using powders I have on hand. Perusing their .38 Special data, I was surprised to see that their lead bullets for the .38 used Linotype for the lead. In their hardness chart, they consider linotype to be BHN of 22-24. Velocities are what you expect for .38s, 700-800fps. Contrast that with other lead data for 9mm, .357 and even the .41 where velocity hits 1200 and they suggest Lyman #2 as their hardness, down in the 15-18 BHN. :confused:

I know you can't read minds, but what do you think Lymann is thinking with this? It's 180 degrees opposite to what most other lead bullet shooters seem to think. I know what & who I'm trusting, but I'm curious...

Q

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rcmodel
January 24, 2010, 06:28 PM
I think they are telling you the bullet weight that mold # will throw with that alloy.

Using softer alloy will make heavier bullets in the same mold.

And I agree it is confusing to see that with no explanation why.

I wish they had just said so, and used Lyman #2 alloy as the base alloy bullet weight the mold will throw for everything.
Or at least pistol bullets anyway.

Linotype would be the base line for rifle bullets perhaps.

rc

243winxb
January 24, 2010, 06:39 PM
I was surprised to see that their lead bullets for the .38 used Linotype for the lead. Misprint comes to mind or you read it wrong. Email Lyman and ask. Take a photo of the page and post it.

warnerwh
January 24, 2010, 06:40 PM
I'm sure curious too. For quite a few years now only my SBH has seen cast bullets as I avoided them like the plague after a bad experience. My knowledge is very limited and I am very confused even after doing a bunch of reading about leading and cast bullets. I'm using some Oregon Trail Lasercast bullets in the Ruger .44 magnum loaded to about 900-1000fps. Leading is just a little and a non issue. The bullets are 24 bhn.

I just started using Missouri bullets 18bhn .357 swc. Velocity is about the same as the .44 load, 900-1000fps, but I get significantly more leading. The .357 is a Dan Wesson and I don't think the barrel is as smooth as the Ruger which may account for the little extra leading.
I just read I believe in Shooting Times online mag that the main cause of leading is the gases getting around the bullet especially in the jump from cylinder to forcing cone. I would like to see some empirical data and real world tests because I don't know what to think. Knowing how to get the least amount of leading is what I'd like to know.

rcmodel
January 24, 2010, 06:51 PM
Misprint comes to mind or you read it wrong.It is not a misprint, and he didn't read it wrong.

Lyman manuals started listing Linotype pistol bullets somewhere between the 45th. and 47th. editions. And are still doing it in the 49th.

I still contend they are only saying what weight the mold throws with the alloy listed.

rc

243winxb
January 24, 2010, 06:55 PM
Very strange. I must remember not to read any new books on casting.

Quoheleth
January 24, 2010, 09:02 PM
I just started using Missouri bullets 18bhn .357 swc. Velocity is about the same as the .44 load, 900-1000fps, but I get significantly more leading. The .357 is a Dan Wesson and I don't think the barrel is as smooth as the Ruger which may account for the little extra leading.

What powder are you using, warnerwh? It usually helps if you have tried to match as closely as possible the powder's pressure data with the bullet. Check Missouri Bullet's FAQ page for an explanation.

In my GP100, I like Titegroup (5 gr is a max load) and it seems to run
@ 1000. I want to try Alliant 2400 - a classic lead bullet powder for magnum performance. I ran a batch of Missouri Bullet with Unique this afternoon, just slightly above minimum (my Lee auto disc throws a charge a little more than max...about 1/2 grain, IIRC, and I decided that was close enough).

Misprint comes to mind or you read it wrong. Email Lyman and ask. Take a photo of the page and post it.

I'm not misreading the manual. I read, re-read, and re-re-read to make sure I wasn't wrong. I'm going to email Lyman tomorrow and get the official word, but I suspect RC is probably on the right track, because running a bullet that hard in low pressure .38 Special loads is counter-intuitive.

Q

MissouriBullet
January 24, 2010, 09:44 PM
I concur with rcmodel as well. My thought is that linotype is one of the few available lead alloys produced with specified metallurgical characteristics with respect to constituent elements and their relative presence expressed as percentages, with the result that hardness of castings made from it is known with precision. In other words, it is purely a reference metal not chosen for performance in any particular caliber but rather because it provides a valid and reliable baseline.

On the other hand, they may all have been crazy drunk when they wrote that section. Who knows?

Quoheleth
January 24, 2010, 10:27 PM
I emailed Lyman a little bit ago. If/when I hear from them, I'll post the answer back here.

Q

MichaelK
January 24, 2010, 11:30 PM
Frankly, I'm sure you can find some guy that will tell you that the perfect .357 bullet must be made with 8% antimony alloy tempered from the mold into 5% powdered milk and lubed with 50% beeswax/50% zebra fat.

Me however, got tired of all the recipes and just use Lyman #2 alloy for everything, from 38 special to rifle bullets. I make #2 alloy by melting 19lbs of wheelweight lead and add exactly 1 roll (1.0lb) of lead-free plumbing solder. The tin content makes beautifully uniform bullets and leading is minimal, even at rifle velocities.

If you want to spend your time shooting instead casting in the garage, make #2 and forget about it.

warnerwh
January 28, 2010, 06:30 PM
Quoheleth: I am using Unique for both my .357 and .44 Dan Wessons. The .44 didn't like it. I have no chronograph but they should both be 900-1000fps.

Quoheleth
January 28, 2010, 06:35 PM
I emailed this question about the listed hardness to Lyman Sunday night.

I recently bought a copy of the Lyman Pistol and Revolver reloading manual. I'm surprised that in some low-pressure cast bullet loads (like .38 Special) a linotype bullet (BHN 22+) is shown, while in other higher-pressure loads, like .357 Magnum or .41 Magnum, a Lyman #2 (BHN 15-18) is shown. What is the rationale for the significantly harder bullet in low-pressure applications, while a softer bullet is used in higher presure applications? Is this more a reflection of what that bullet mould will throw with that hardness of lead, or is the manual actually recommending bullets of that hardness in those applications. I will look forward to hearing form you.


Here is the reply I received today:

Basically the data was developed at different time and common alloys that were on hand at the time were used. Currently we would use #2 for all of these calibers. There really is not a pressure difference between the two types of metal as they are so close in hardness. Either could be used without trouble, although you are correct that the softer #2 would usually be choosen over linotype for lower pressure/velocity applications.

In other words, the way I read it, it's "shoot it and don't worry about what the lead's hardness might be."

Q

Jesse Heywood
January 28, 2010, 07:23 PM
Thanks to help from some here, I was recently educated about the role lubrication plays in leading the barrel. If you are buying bullets cast by someone else, apply a thin coat of either Alox or Rooster Jacket. At low velocities my leading issue was gone.

SteveW-II
January 28, 2010, 10:31 PM
I don't think there really is any hard and fast rule about what
hardness of lead alloy you should use. You have a couple of
variables to play with, hardness is just one. Bullet sizing is
another. I think it depends on the task at hand.

For semi-autos, I keep the alloy as hard as possible because
the rifling on most semi autos is shallow, designed to keep
friction low for jacketed bullets. The harder the alloy, the
more likely it is to grip the rifling. If the lead is soft, high
velocity semi autos may accelerate the bullet at a speed
beyond which the lead can grip the rifling, effectively
stripping the bullet. That will lead your barrel very quickly.
A bullet of Linotype is also likely to survive the journey from
the magazine, up the feed ramp and into the chamber
without deforming. Linotype is the most cost effective alloy
for hard bullets, so I use it.

However, the original question was about revolver bullets.

When casting for revolvers you need to know the dimension
of the cylinder throats, the max diameter of the barrel down
into the groves and to a lesser extent, the speed of the
round. The real objective is to make sure the bullet
effectively seals the barrel as the propellant gas pushes out
of the muzzle.

Let me give an example. I have a revolver whose cylinder
throats measure .450" on all chambers. The barrel measures
.455" down into the groves (a clue to its make). As the round
is fired, the bullet is 'resized' by the cylinder throat to .450"
as it makes the jump across the cylinder/barrel gap. If the
bullet is hard cast, at best it will rattle down the barrel barely
engaging the rifling and display poor accuracy. At worst, it
will still show bad accuracy AND lead the barrel badly. Apart
from lead fragments around a forcing cone, barrel leading can
be caused by hot propellant gas pushing past the bullet,
blowing molten lead ahead of the bullet which, as it cools, is
then smeared onto the barrel by the bullet as it passes by.
I have heard this described as ‘cutting’. For this gun to shoot
well and accurately, a bullet with a hollow base cast from soft
lead is required. The propellant gas expands the soft lead
bullet ‘skirt’ to seal the bore and grip the rifling. The lower
the gas pressure, the softer the lead should be. A hard cast,
hollow base bullet would act the same as a flat base as the
pressure wouldn’t expand it. This is the original ‘Mine ball’
concept.

The Webley is an extreme example, but many S&W 45 Colt
revolvers have cylinder throats of .452” and barrels of .454”.
This is why so many cast bullets for 45 Colt are often sized
to .454" but jacketed bullets are .452".
For those guns, a soft bullet, sized to the diameter of the
cylinder throat, is likely to bump up (or obdurate) and seal
the bore. If you get leading in those guns, the answer is
likely to be softer lead alloy, not harder. With such revolvers
a .452” bullet will grip the rifling in a .454” barrel. Accuracy
won’t be an issue until the leading makes it so.

If you are lucky enough to have a revolver whose cylinder
throats match the largest barrel dimension or (even better)
are about one thou larger than the barrel, then size the cast
bullets to the same diameter as the cylinder throats. My
Ruger GP100 is a good example. Now, the hardness of the
lead matters a little. My rule of thumb is that if the muzzle
velocity is more than 1000 fps, then the harder the lead the
better. I use 20:1 for below 1000 fps, Linotype for above.
That is, unless you are using cast bullets with gas checks.
Then, I always use hard alloy as soft lead doesn’t give the
‘crimp’ on the gas check anything solid to bite into.

Then, there are revolvers that fire rounds designed for
semi-autos. A S&W 625 in 45 ACP is an example. The barrel
is likely to be shallow rifled (to prevent a jacketed bullet from
sticking in the forcing cone and letting the propellant gas
blow out of the cylinder/barrel gap) but the same mismatch
between cylinder throats and barrel dimensions is possible.
Measure them and use hard cast bullets if the throats are
bigger than the barrel. If not, it’s likely the gun won’t shoot
too well and you will need to experiment to find the right
alloy/size/velocity combination.

Cast bullets for lever actions are another story, but in
general, hard alloy sized at one thou over the maximum
barrel dimension is a reasonable guide. I prefer gas check
cast bullets in lever actions.

But anyway, if you have got this far, you are likely to think I am rambling.

Steve.

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