23 January 2010, 04:13
lawndartThanks guys,
Even the best made, non sealed ammunition will equilibrate with the surrounding relative humidity (RH) after ten to thirty weeks; hence the admonition to store ammunition in a cool area with a RH of 40% to 50% (same RH as when it was made).
When I finally get healthier (or die trying), I fully intend to go ahead with making commercial "Safari" ammunition. Once a PH opens the sealed can that the ammo comes in, it may knock around on the dash of his bakkie for
years. NATO spec'ed ammunition and the Safari ammunition made by Federal are both sealed with asphalt for the bullet, and lacquer for the primer.
The "belts and suspenders" approach is to keep the powder from equilibrating with a local RH of 10% (makes the powder too hot - kaboom) or 90% (pfffft - semi squibb).
I think I will let the asphalt partially dry. Then I can push any needed spacers beyond the sealer without gumming them up. Seating the bullet (with maybe a touch of asphalt around its base) should provide a 1/2" zone of sealer.
The biggest thing will be to originally seal the cartridges in a can, and keeping that can in a cooler place until needed.
Also, if a visiting hunter leaves his ammunition for the PH, having it well sealed will extend its "shoot by" date for a year or two.
I have been well educated on the difference between making personal use ammunition and commercial ammunition. The labor doubles, and the liability increases to infinity.
LD
Edited for spelling.
24 January 2010, 05:42
lawndartFrom one middle aged former chemist to another chemist, I very much appreciate your thoughtfull answers Doc, and my other esteemed colleages.
More than one, boredom in some odd corner of this old world had myself and the other riff-raff pulling apart cartridges, mainly to get the powder out of blanks to triple charge reinforced grenade simulators.
All the ball ammo up through 50 BMG had an asphalt sealer, so I shall experiment with that (rigorously). I believe that the asphalt sealer has more give in it as the case neck and bullet heats, and then cools.
A bullet/neck fit that was so tight as to prevent gas exchange would be very galled. I shudder to think how much (and how varied) the force to seperate the bullet during firing would be.
We are closing in on some answers; I am gratefull for all this excellent input. I do solicit more. I know, I know, damned scientists are never satisfied. Soon the production engineer and the marketer in me will say, "okay, stop pondering and lets start manufacturing."
I am interested to know the best source of suitable lacquer, and what dies to use in it; aniline?
Doc, I would appeciate a link to the rest of Sniper 66's article. I would guess he has a touch of military time.
26 January 2010, 02:29
Doc224/375John ; Sniper 66 is MIA at the moment ! ??. ( Yes Aniline dye is soluble in Lacquer an Alcohol )
Ammunition research in the first
postwar years was inspired not only by new
requirements, but also by the problems encountered in
preserving ammunition, especially propellants, stored
after the Armistice. Research proceeded in three areas:
determining the stability of smokeless powder, studying
the effects of long term storage on stability, and creating
more efficient methods of drying. A good deal of
valuable information on these substances was
assembled at Picatinny Arsenal, NJ, before 1926,
notably that on feasibility of the vapor method of drying,
which reduced drying time from months or weeks to
days. But a more permanent solution of some phases
of the powder storage problem would be to develop new
non-hygroscopic powders, which because of their
chemical composition would not absorb enough
moisture to affect their ballistics or chemical stability
even when stored in a damp atmosphere. If, at the
same time, flashless and smokeless qualities could be
incorporated, the advantages would be even greater.
Thus the search for flashless non-hygroscopic (FNH)
powders was vigorously pushed. The DuPont Company,
under a special agreement with the Ordnance
Department, followed one route of investigation, while
Picatinny Arsenal followed another. Each achieved
considerable success. The peacetime development of
complete single-base and double-base non-hygroscopic
powders, flashless in many weapons, was one of the
most useful accomplishments of the Ordnance
Department before 1940. Traditionally, British
propellants have been of the double-base type
developed prior to World War II and designated as
cordites. The cordites were made up of varying
percentages of nitrocellulose, nitroglycerin, and mineral
jelly. The mineral jelly (petroleum jelly or petrolatum)
acted as a stabilizer. A sample of British MD cordite
has been found to be of apparently unchanged stability
after 30 years of temperature-climate storage.
2-12
Downloaded from
http://www.everyspec.com on 2010-01-25T21

02.
TM 9-1300-214
The search for a compound that was both smokeless
and flashless had its beginning in the requirement
established by the US Army Ordnance's Westervelt
Board in 1919. In the early 1920's, ordnance scientists
offered the using arms samples of nitroguanidine, which
to a degree unobtainable in any other known propellant,
had both properties. But nitroguanidine gave off such
noxious ammoniacal fumes in combustion that the Field
Artillery vetoed its use. The Ordnance Department, with
no customers in prospect, then abandoned all thought of
building plants to make nitroguanidine. But ammunition
specialists found no satisfactory substitutes. Adding
potassium sulfate to propellants for antiaircraft fire,
where flashlessness was all important, helped to solve
that problem. However, it was no answer to the demand
for a completely smokeless and flashless propellant for
field artillery where smoke would obscure a gunner's
vision and muzzle flash would reveal the tank or battery
position.
MIL-DTL-1318C (AR)( Specs .50 cal M17 /tracer )
3
2.4 Order of precedence. In the event of a conflict between the text of this
document and the references cited herein, the text of this document takes precedence.
Nothing in this document, however, supersedes applicable laws and regulations unless a
specific exemption has been obtained.
3. REQUIREMENTS
3.1 First article. When specified (see 6.2), a sample of the M17 cartridges shall
be subjected to first article inspection in accordance with 4.3.
3.2 Conformance inspection. A sample of the M17 cartridges shall be subjected
to conformance inspection in accordance with 4.4.
3.3 Cartridge. The cartridge shall comply with all requirements specified on
Dwg 7672165.
3.4. Bullet extraction. The force required to separate the bullet from the cartridge
case shall not be less than 200 pounds.
3.5 Residual stress. The cartridge shall not split or crack when subjected to a one
percent mercurous nitrate solution for 15 minutes.
3.6 Waterproof. The cartridge shall not release more than one bubble of air when
subjected to a pressure differential of 7.5 pounds per square inch (psi) for 30 seconds.
3.7 Accuracy. The average of the mean radii of all targets of the sample
cartridges, fired at 600 yards, shall not exceed 12.0 inches or, when fired at 200 yards,
shall not exceed 6.25 inches.
3.8 Action time. The action time (overall primer ignition, propellant burning,
plus the time taken for the bullet to exit the barrel) of the cartridge, conditioned at 70°F
± 2°F, shall not exceed 4 milliseconds (ms).
3.9 Velocity. The average velocity of the sample cartridges, conditioned at 70°F
± 2°F, shall be 2,905 ft/sec ± 30 ft/sec at 78 feet from the muzzle of the weapon. The
standard deviation of the velocities shall not exceed 36 ft/sec.
3.10 Chamber pressure. The average chamber pressure of the sample cartridges,
conditioned at 70°F ± 2°F, shall not exceed 65,000 psi.
3.11 Function and casualty. The cartridge shall function without casualty.
3.12 Air tightness of base closer seal. The bullet shall not release more than one
bubble of air under the application of a pressure differential of 2 psi for 5 seconds
Abstract: Waterproof sealing of the sabot and primer of the XM645 Cartridge (SFR) has been achieved using a pigmented resin-solvent formulation. Firing tests conducted on experimentally sealed rounds have given every indication that seals are acceptable. Efforts to effect sealing of the sabot by means of commercially available dry-shrink or heat-shrink preformed plastic caps, or to mold caps having the desired wall thickness, were successful. A rapid, reduced pressure leak test was employed. (Author)
http://www.stormingmedia.us/98/9805/0980509.html Unfortunately the remainder of this article was Unavailable ( FRANKFORD ARSENAL PHILADELPHIA PA. ) !!!.26 January 2010, 04:52
lawndartThis is all hugely helpful, and even more interesting.
I will research all of this stuff in detail, and report back on my efforts and
Results.
Pictures even.
WESR,
Get a copy of the new Norma reloading manual. An engineer from Bofors/Nexplo tested factory ammunition that had equilibrated with a range of RHs. Dry fired hotter and moist didn't do so well.
IIRC the actual powder has water in it to the tune of 0.5% up to 4% or so, depending on RH.
I pulled some M118LR apart last night. Yep, asphalt up front, and lacquer in the back. Also, crimped primer pockets. The thinking goes that in a pinch, the "sniper" ammunition can be used in the nearest machine gun. History shows that things usually work in the opposite direction!
Thanks again Doc. I got off in the weeds with biochemistry and then molecular biology. That in turn led to medical school, duh. Shoulda, woulda, coulda stopped while I was ahead

.
PS Time to order some Gilsonite
PPS Doc, where is a good place to order a gallon or so of Nitro Lacquer? Thanks.