Fast vs. Slow powder

[JohnH]

JohnH,
I agree whole heartedly with you. Fast and Slow powders are just tools in your tool box and different powders for different jobs. It really is that simple. But being a caster and a reloader I want to know why things happen and so sometimes I just think/explore things to their logical conclusion ( and sometimes not so logical conclusions).
Calvin

I understand. One point I was trying to make and prolly didn't state well is that poor performance is possible regardless of what powder speed we are using. Exceeed the limits of the alloy, throat, barrel dimensions, and you'll get lousy groups. I can shoot the 312185 sized to .310 in my M44 and get exellent results, so long as I don't exceed 1300 fps. Go above that, at that size, and I get patterns not groups. Run the boolit through a 314 sizing die, or simply use LLA and it fits proper and I can drive it as fast as I care to push it up to about 1900 fps. I don't shoot the gun faster so I've no idea what happens after that.

I have similar experience with my 30-30 WCF 340 Savage. 10 grains of Unique makes circa 1200 fps and yeilds consistant 1 1/2" groups. 37 grains of H205 give me 1950 fps and.....you guessed it, 2" groups. Both these with the Lee 312-185 sized at .310. I plan on trying out the boolit done up in BBBB fashion with the second load on a whitetail this year.

The great problem I have with Mr Lee's book is twofold:

First and most importantly he doesn't actually reveal anything that wasn't known before his publication. He borrowed heavily from Veral Smiths work and that of the Cast Bullet Association. At one point in time there was much disscussion about this. To his credit, he did put this information together in a package that was much more readily available to the general shooting public.

Second, reading his articles leaves one with the impression that Mr Lee came up with all this info himself, and it just ain't so. His writing leaves me with the impression he is quite impressed with himself, and my experience with folks with such attitudes has been less than enjoyable. At the least it would have been nice if he had given due credit where, and to those to whom it was due.

The one thing he didn't say about the use of fast powders in rifle cartridges, is that peole have been doing so for a long long time with very good results, kind of the same old "Out with the old, in with the new" mantra that everyone that is selling something uses if you listen to what they are saying.

These days I listen to ny gun, it'll tell me more of what it needs that any 10 Mr Lees ever could.

[mag_01]

Lee's writings have merit to those who can understand them --- Don't get lost in the terminology -- I like what some have said here and disagree with others -- Perfect world assumptions and real world results may not be one in the same by a long shot. If one is to read -- understand what is read-- evaluate its merit --- apply what seems as value --- using it as a tool to better our sport of reloading and shooting.

As far as using fast or slow powders each individual will determine where he wants to be for his desired results. They both have merit and should be used as the shooter prefers.


There has been a lot of good input into this forum on this subject and it is beneficial to its members. good group airing its thoughts thanks all _ Mag_01

[Bret4207]

This discussion goes well beyond Lee and his scribblings. I really don't think there is ANYTHING to do with cast boolits or shooting in general that hasn't been known for close to 100 years or more. But when someone "rediscovers" it and sticks a patent on it, he "owns" the idea for 20 years. The fast/slow powder issue is simple- light loads=fast powder, heavier loads=slower powders. There, thats over with. Feel free to disagree.

My curiosity has to do with the "whys" as JohnH said. 45 2.1 has made some statements and I'd like a clearer understanding of what he means. I don't shoot fast loads much, heck I don't even shoot at all much anymore it seems! (Kids, work, farm, work, kids) But understanding what he is trying to say matters to me, so I'll make the effort to see it through.

An example of how stubborn I can be on this- I'm still working my way through "The Bullets Flight". It's going on 6 years and so far my margin notes outnumber Harry Popes!

[45 2.1]

My curiosity has to do with the "whys" as JohnH said. 45 2.1 has made some statements and I'd like a clearer understanding of what he means.

I lose track sometimes and I haven't looked at this thread for awhile. Which and what..............................

[MtGun44]

I am in total agreement with Buckshot. I have found so many
examples of 10.0 Unique or a bit more in some (like 12-13 in .45-70)
big cases being very accurate with a lot of different bullets.

There is something special about 10 gr Unique. It just works.

It is worth trying in any caliber that it is a safe load in, which is
basically 44 mag and up in pistols, and essentially any of the
7mm or greater rifle cartridges. I have seen many cases where
it is one of the most accurate or THE most accurate load in
both pistols, pistol caliber carbines and rifles.

A product that actually lives up to it's name!

Bill

[MtGun44]

Most metals have the same strength in compression as in tension.
I have never actually run lead on an Instron, but I'd assume it
behaves like steel or aluminum in this sense until I have some data that
counters it.

Shear strength is 1/2 tensile strength, due to geometric considerations.

So if we are shearing the lead alloy by the rifling load, then it will
fail at 1/2 the tensile/compressive strength. However, if we are
trying to deform the bullet we need to exceed the yield strength,
not the tensile strength (which is the failure point, not the point of
permanent deformation, which is the definition of the yield stress).
Now, tensile failure is easier to imagine than compressive failure,
but in most cases we are interested in the point where the material
stays permanently deformed, which is the yield point. This is the
same for most (all?) metals in tension or compression. An example
of a material that does not conform to this is ceramics. Ceramics
essentially ONLY fail in tension, never in compression. However,
with extremely high compressive loading, small areas will start to
develop tensile stresses due to Poisson effects and the ceramic
will fail "in compression" but due to localize tensile stresses starting
a crack.

Hope this helps, not hinders. The key point is that engineering terms
have evolved to mean a specific thing and when used incorrectly,
they can cause more confusion than enlightenment. I don't like
to be pedantic but we really DO need to be sure we are using
our terms correctly or we cannot effectively communicate. And - like
it or not, we are involved in a hobby where some engineering does
come into play from time to time.

Bill

[Bret4207]

Mtn gun- Thank you. Believe it or not you cleared some of the murky waters for me. I'm following better now.

[45 2.1]

Most metals have the same strength in compression as in tension. I have never actually run lead on an Instron, but I'd assume it behaves like steel or aluminum in this sense until I have some data that counters it. Bill

Not, assumptions like that without checking actual results get a lot of people in trouble.

[38-55]

Hey Guys,
On my never ending source for knowledge ....I ran across this bone that I'll throw into the pot...
Kinda cool stuff really.. http://www.ldaint.org/technotes5.htm
Stay safe
Calvin
Ps lead is far more ductile than either steel or aluminum.........so it's compression and tension properties are way different

[Char-Gar]

mtgun... Thanks for that post, it was very helpful. I don't have any kind of hard science background and all of these terms had me "bumfuzzled". I now think I understand what term means what. I printed off a copy of your post for my files, so I can reresh if necessary. Thanks again.

[JudgeBAC]

My thanks to all for a very informative discussion. I have learned a lot reading all of the informative posts even though everyone does not agree.

[MtGun44]

45 2.1,

I agree with you that assumptions are not desirable. If we are going
to assume (we all know what that means) we need to make sure we
know that we are on somewhat shakey ground, and watch out for
any information that may correct our assumptions if they prove to be
incorrect.

So - it is possible that lead has a different yield stress in compression
than in tension. I really would like to know if that is the case or whether
it behaves like other metals and has the same yield in either loads,
or near enough for practical purposes.

Does anyone have a good reference source on lead yield stress in
tension vs compression?

Bill

[felix]

Bill, I think the info being sought could be useful when we can stretch the meaning of tension to include the flying-apart syndrome during rotation. ... felix

[MtGun44]

Felix,

You are right that the 'flying apart' load due to rotation (centripital acceleration or
centrifugal force) is a tension load. The boolit is also subjected to a lot
of compression from the rear, which also tends to make the bullet get "fatter"
(obturate) to fill the bore. This 'getting fatter when compressed' is officially
called Poisson's effect, for the Frenchman that discovered it. The Poisson's
ratio (a measure of how a particular material acts in this way) is a key piece
of info when doing advanced engineering calculations like stress analysis.

I think the original discussion of pressure vs BHN, which makes a numerical connection between boolit hardness and it's performance under pressure
loading is a good one. It seems very logical that too hard a boolit and/or
too low a pressure peak and the boolit may not obturate (slug up) to fit
the bore well and poor accuracy and leading are likely.

On the other end, it also seems very reasonable that with too soft an alloy
and/or too much pressure and that you can overload the metal and strip the rifling, excessively deform the boolit, or other bad things.

I don't have any info to dispute the numerical relationship reported by
others, so I'll assume (that word again) it is a correct and useful relationship
unless I run into problems matching it with testing results.

The one fly in the ointment seems to be knowing the pressure in the
case. Some folks seem to know the pressure in the case, and I have
wondered how they come up with those pressure values. Since I am
still learning, I will just listen and try to put all these pieces of info together
and see what I can do better in the future.

Anybody that can explain how they come up with case pressures for
particular loads (other than by measuring in a pressure gun!) would
be very much appreciated. I'd like to learn more about this, as it seems
only very roughly 'guessable' by me.

Bill

[grumpy one]

You can get some simple illumination from the short not-very-technical notes here:
http://www.ldaint.org/technotes5.htm

Because pure lead is exceptionally prone to creep it acts more like a plastic than a metal, and its tensile strength is not much more than half its compressive strength. However both are pretty negligible over the long term (say 20 years of continuous stress). Under any stress higher than a few hundred PSI lead is in a state of flow, and has to be analysed as a viscous medium - that is, a plastic. The stress it can withstand in the short term is thus very much higher than it can sustain in the medium or long term.

For us as bullet-makers the main issue is how fast lead deforms when exposed to many thousands of PSI for no more than 5 milliseconds. This is strictly a viscous-flow situation.

[felix]

Yep, GO, is correct, Bill. At least, by my thinking about the parameters. The key element that is missing is the time delta, from start to final deformation allowed by the grooves. This is one reason different powder speeds (ignition, mainly) can alter that so-called formula into never-never land. ... felix

[MtGun44]

Grumpy one,

Thanks for the reference, a good one.

In my work, I often do very detailed stress analysis of electronics, and
one of the real saving graces of tin-lead solder (63-37) is that it creeps
to relieve stress at normal temps over relatively short time frames, like
hours to days depending on the exact temperature. This eliminates
the stresses that come from heating the assembly up while soldering,
which is not done one at a time but with a wave tank or other bulk
heating method which tends to lock in stresses which may be damaging.
Solder creeps these away, making the electronics more reliable, a good
thing in military electronics.

HOWEVER,
Creeping isn't too relevant to boolits, tho - as you point out we are done
in a few milliseconds.

Also, we are dealing with significantly alloyed lead, not pure lead. And
in many cases, heat treated lead alloy - WAY different than pure lead.

Bill

[45 2.1]

I don't have any info to dispute the numerical relationship reported by others, so I'll assume (that word again) it is a correct and useful relationship unless I run into problems matching it with testing results.
It's better to test and verify, rather than assume anything.


The one fly in the ointment seems to be knowing the pressure in the case. Some folks seem to know the pressure in the case, and I have wondered how they come up with those pressure values.
Published in the Lyman manuals among other places.

Anybody that can explain how they come up with case pressures for particular loads (other than by measuring in a pressure gun!) would be very much appreciated. I'd like to learn more about this, as it seems only very roughly 'guessable' by me.
There are strain gauges that can be glued onto the chamber area to do this, several high level experimenters do this.


What you need to look at besides the alloy considerations, which vary greatly depending on composition, individual percentages and hardness, are the mechanics involved of getting the boolit into the barrel. A jacketed bullet has a very soft core, in comparison to our alloys, with a tough "skin" of high hardness (50BHN minimum) that takes the rifling, nonwithstanding all the tapering, notching and fluteing of the jacket material to promote expansion. There are some alloys that can be heat treated that will have a tough linotype hardness outer shell with the core at the original soft hardness. Much like a jacketed bullet, but you can make them yourself and tailor them to your requirements. Try it out yourself, all it requires is a hardness tester. This will get you much farther along getting higher velocity than most things will, especially with the more difficult calibers that are loaded.

[Pat I.]

There are some alloys that can be heat treated that will have a tough linotype hardness outer shell with the core at the original soft hardness. Much like a jacketed bullet, [/B]

Unless you're case hardening I don't think this is quite right, at least it hasn't been the case in my tests with my mixes.

[45 2.1]

Unless you're case hardening I don't think this is quite right, at least it hasn't been the case in my tests with my mixes.

At least three of us have found what i've said to be true. Your methods and alloys may not be up to it though.