From: gmk@falstaff.mae.cwru.edu (Geoff Kotzar)
Subject: Re: Downloading Centerfire rounds
Organization: Case Western Reserve University

In article <35692@mimsy.umd.edu> snitor!petert@uunet.UU.NET (Peter Toth) writes:
#In article <35665@mimsy.umd.edu> bercov@bevsun.bev.lbl.gov (John Bercovitz) writes:
##In article <35613@mimsy.umd.edu>
## uunet!clodii.columbiasc.NCR.COM!keith@cs.UMD.EDU writes:
##
###   I am curious about what would happen if I were to download a .270cal
###round from my normal 50 grns. to say...about 30 grns. Would this be a
###dangerous thing to do?
##
##You could probably get away with it for years, but enough people have
##blown up their rifles this way that it's not worth taking the chance.
##The theory of why these low-loading-density detonations happen is not
##well developed.  I think the best explanation is to be found in 
##"Pressure Factors" by Brownell, Wolfe Publishing.  c1990?
##[...]
#
#How about: you are more likely to see this problem with "fast" powder.
#
#The problem with the half empty case is that you get flame propagation
#end to end faster than you can say "Oh #@%*!" ;^)  If it's a slow powder,
#no matter, or not much; if it's a fast one, don't do it next to me =%0.
#
#petert

John Bercovitz is right about which burning rate powders are susceptible
to low loading density explosions: it is the slow or extra-slow powders.
For a long time people did not believe that smokeless powders could
detonate and attributed the wrecked rifles to reloads that had been loaded
with the wrong powder. When they finally accepted that it was happening
to too many conscientious reloader using Hodgdon's 4831 to be poor reloading
technique all sorts of explanations were heard. One was that the violence
of the primer going off would ignite and shatter the grains of powder since
they were not completely constrained. This resulted in a "moderate" load of 4831
being converted into an excessive load of something like 4227. The really big
problem was that it could not be reproduced on demand in the ballistic labs
so nobody could even begin to test out the hypotheses. Within the last two
or three years there was an article in Handloader Magazine by a fellow who
was able to produce these pressure excursions - also named at one time SEE
for secondary excursion explosions I believe -  on demand in his rifle. One
point that comes out in the "Pressure Factor" articles is that the excursions
are occurring with these slow powders with great regularity but it requires
a piezoelectric pressure transducer and an oscilloscope to monitor them. The
old crusher system for measureing pressures missed the lower amplitude but
more common ones entirely. It isn't a question of are the pressure excursions
occurring with the reduced loads of slow burning powders but rather how
extreme are the amplitude fluctations. People were only paying attention
when rifles were destroyed.
 

From: gmk@falstaff.MAE.CWRU.EDU (Geoff Kotzar)
Subject: ww-296 and reduced loads
Organization: /etc/organization

I thought you might like the latest in the (never ending) saga of 296 and
"reduced loads". I just got off the phone to Dave Price, a customer service
or company spokesman type, at the Winchester Group of Olin Corp.

First the definition of the "reduced loads" we discussed. Winchester lists
only one load, the maximum load, for their powders. They state the following
explicitly in BOLD print: You must start 10% below the suggested load and work
up to the maximum load carefully, except as follows... (page 36, 12th Ed.).
This is at the start of the "Metallic Cartridge Reloading" section and applies
to rifle and pistol data. Note that the "suggested load" and the "maximum load"
are one and the same thing. The exception that I have omitted above is very
important to what follows. It reads:

"The loads for 8mm Mauser and .338 Win Mag must be used EXACTLY as shown. NO
reductions in powder charge or change in components should be made because
such changes can cause dangerous pressures." (The emphasis above is mine.)

Yet on page 40 where the data for the two cartridges is located, a slightly
different version of the warning is listed. "CAUTION: Loads marked with an
asterisk (*) (8mm Mauser and .338 Win Mag only) must be used APPROXIMATELY
as shown. Reduction in powder charge not to exceed 10% or change in components
should be made because such changes can cause dangerous pressures." (Emphasis
is again mine.)

So what does this have to do with 296 loads in pistols? Does Winchester list
296 as a suitable powder for use in the 8mm Mauser or the .338 Win Mag? No!
But they do list two loads for rifle cartridges on pages 39 and 40. Speci-
fically, for the .30 Carbine and .30-30 both with 110 JHP's. And curiously
enough there is not one word of warning about not reducing these 296 loads
10% and then working up to maximum.

But on pages 45 and 47 in the pistol section, Winchester lists the following
warning: "Do not reduce powder charges with 296 powder. These loads must be
used exactly as shown. A reduction in powder charge or change in components
can cause dangerous pressures." (My thanks to Henry Schaffer.)

Do the inconsistencies in these warning bother any of the old hands out there?
I should think that a newcomer would be intimidated all to hell. The three
magnum pistol cartridges (.357, .41 and .44) are all straight walled cases
as is the .30 Carbine and all have loads listed with 296 and bullets of equal
sectional density. So now let us ask the following questions. If I load my
.357/.41/.44 for a Marlin 1892 can I then cut the max charge back by 10% to
make my starting load? And if I load my .30 Carbine cases for use in a Ruger
(boo, hiss) Blackhawk do I have to use the maximum load exactly as Winchester
published it since it now a "handgun" cartridge? For those not familiar with
these cartridges, they all are magnum class cartridges (max operating pres-
sures of nominally 40k CUP; .357 operates at a max of 46k CUP), they all have
case lengths of 1.290 inch (again nominally) and they all use bullets of
nominally the same sectional density. The only substantive difference between
them is that the .30 Carbine uses a small rifle primer instead of a pistol
primer and that might account for the difference but I doubt it. Of the five
cartridges for which Winchester lists 296 loads, only the .30-30, which is
a bottle-necked case, should behave differently.


So that was as far as I got in questioning the "reduced loads" issue. I had
wanted to ask a lot more questions. Like:

1) Why the inconsistent warnings and what exactly did they signify. Different
   testers' observations, different writers, carelessness?

2) Could the maximum loads listed be reduced 10% safely to form starting
   loads?

3) Exactly what is the form of the problem if the loads are reduced more
   than 10%? Was Winchester realy saying that catastrophic destruction of
   a firearm was the risk of using less than maximum charges of 296?

4) Was Winchester saying that the "reduced" starting loads in all of the
   other manuals were jeopardizing reloaders' firearms?

The answers were far from what I had hoped for.

1) Regarding the inconsistent warnings he said that Winchester had been
   publishing the same info for the last decade and was aware of them.
   But he would pass my concerns on to them. Big deal!

   His answer was not exactly accurate. I went back and looked at my old
   Winchester loading manuals. I have numbers 1-4 and 11 and 12. I had 9
   and 10 at one time but have since lost them. The second printing of #1
   dated 1973 is the first to list 296 loads, and with the exceptions of
   the 110 JHP load for the .30-30 and the .41 Mag loads the loads listed
   in #12 are the same as the 1973 data. The only warning listed at that
   time was for the 8mm Mauser and the .338 Win Mag. The second edition
   is dated 1976. With that edition the .30-30 load appeared along with
   the warning about 296 loads in the revolver cartridges. (By coincidence
   the editor for the second edition was Ed Matunas. This is the same Ed
   Matunas who is now the editor for the Lyman 47th edition manual and who
   was responsible for the deletion of all 296 loads in that manual.) With
   the manual dated 1978, which I believe is #4, the .41 Mag data was included
   but there was no change in either of the two warnings. So some time after
   the 4th and 1978 the ambiguous warning concerning the two rifle car-
   tridges was added. I am inclined to wonder if Winchester's reticence is
   not tied somehow to company inertia and the lack of active load develop-
   ment. Until the introduction of the 10mm loads in the 11th Ed. Winchester's
   load development with 296 had been pretty stagnant.

2) As for being able to safely reduce the listed charges 10% to form starting
   loads, Price told me "the general wisdom here is not to reduce 296 loads
   more than one (1) grain". Contrast this with the answer to question #4.

3) The dangers involved? All Mr. Price would say was that Winchester felt that
   296 was more "sensitive" than their other Ball powders to its loading condi-
   tions. He wandered off into a discussion of the rapid pressure increase
   as the powder level reached the base of the bullet. This is consistent
   with others' observations already in the literature but I had been asking
   about charges less than maximum, not compressed charges. I found it very
   hard to keep this man on the subject.

4) What about the data in the other loading manuals? I did not get to ask
   this question, but the indirect answer was quite humorous. He could or
   would not answer my questions without talking to someone else first. When
   he called back he could not be convinced that I was asking a general
   question about 296 behavior. Rather he wanted to know for which cartridge
   and bullet weight I needed loading info. I played the game and said .44
   Mag with a 240 JHP. And the data that he supplied to me was right out of
   the new Hodgdon and Hornady manuals. He had them on his desk. When I heard
   this I asked about the Speer data and that is also perfectly acceptable to
   the Winchester people. Since Lyman's data is generated with a pressure gun
   it would also have been accepted by Winchester, so why Lyman dropped 296
   from their data in the 47th edition manual is not clear. It is tempting
   to speculate that it is tied to Matunas' prejudices since none of the
   other companies seem to be afraid of 296.

   In fact, I can find no warnings concerning 296 in the 4th Ed. of the
   Hornady manual or in the No. 26 Hodgdon manual. Remember that these
   are the manuals from which Winchester will be quoting you data if you
   call them. The only warning that I could find for 296 is in the Speer
   manual #11: maximum charges must not be reduced more than 10%. There
   is a similar warning for the Hodgdon version of 296 namely H-110: it
   should not be reduced more than 10% below maximum. To be fair in this
   discussion, the previous Lyman manual, #46, listed the following for
   296 loads: "The manufacturer cautions against using reduced loads with
   this powder. A reduction in powder charge from the listed weights
   can cause dangerous pressures." Which sounds like a simple repetition
   of the Winchester warning. What does Sierra have to say about 296 in
   their 2nd Ed. from 1985? Nothing. Ditto for Nosler's 3rd and RCBS's
   Cast Bullet Maunal #1.

   How much below the maximum load can you go and still be safe? A survey of
   the loading data in the Hodgdon, Hornady and Speer manuals for magnum
   pistol cartridges is somewhat ambiguous. One grain, ten percent, or what?
   Speer starts either 1.5 or 2.0 grains below max for everything from .30
   Carbine to .454 Casull; and it does not necessarily correspond to the
   value of the maximum. For the .30 Carbine the range of powder charges for
   the 110 JHP is 13.0 to 15.0 grains. For the .454 with the 200 JHP the
   powder charge range is 39.0 to 41.0 grains. Hornady allows a much larger
   reduction from maximum for some loads, both in absolute values and as
   percentages of maximum. For a 125 gr .357 load the charges run 18.8 to
   20.9, for the 265 gr .44 Mag load the range is 20.2 to 23.1 and for the
   .445 SuperMag with the 300 gr XTP the charge range is 24.4 to 29.4, a
   whopping 5 grain (or 17%) reduction. Hodgdon likewise gives a 2 or 3
   grain range for many of the magnum pistol loads but lists a very narrow
   range of 14.0 to 14.5 for the .357 Mag with 158 gr JHP's. BTW, this
   particular change in load results in a 10,000 CUP change in pressure,
   for both 296 and H-110.

   Until Winchester is willing to commit themselves and clarify exactly what
   their warning means relative to 296 we are going to have this cloud hanging
   over us. I seriously doubt that they ever will since the warning goes back
   over 16 years and corporate memory simply isn't that long; technicians
   retire, and documentation can be inadequate especially with copper crusher
   systems of pressure measurement. It will be interesting to see if Winchester
   updates its warnings to reflect the current level of knowledge of the other
   suppliers of reloading info. The more relaxed warning for the 8mm Mauser
   and .338 loads is the newer of the two for those cartridges and it is
   consistent with the way the other data manuals treat 748 and 760 loads
   for those cartridges. Furthermore it will be interesting to see how they
   reconcile the warning for the pistol cartridges with the total lack of
   warnings for the two .30 rifle cartridges cited above.

   As I find out more about this I will keep you posted. BTW, Winchester
   has a surplus powder on the market called WC-820 which is a surplus
   version of 296. The original purchaser(s) are not known to me but I
   have seen a number of different lots of slightly varying burning rates
   which have all been faster than cannister 296 by 10 to 15%. The packages
   are marked to start well below 296 loads and work up. So much for Winches-
   ter's warnings.


geoff kotzar