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#Post#: 16--------------------------------------------------
Goodbye Brass
DIR By: allmanav
Date: February 17, 2017, 1:34 pm
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Let’s skip the appetizer and get right to the meat and potatoes
of a manufacturer’s claims for a new cartridge case technology
to replace the 150-year reign of brass. Here’s what Shell Shock
Technologies (SST) says about their two-piece,
nickel-aluminum-stainless steel 9mm Luger NAS3 cases:
Stronger, cheaper and half the weight of brass.
Greater corrosion resistance.
More internal volume.
More consistent ignition.
+P velocities without +P pressures.
Cases won’t stretch, no trimming required.
Withstands 40 or more reloadings.
Picks up with a magnet.
Can be anodized different colors for instant ID.
The NAS3 requires unique flaring and sizing dies (left to right)
that use a synthetic rod “spring” to push cases, rather than
pull them, from the dies.
Taking the last two claims first, OK, it would be pretty handy
to effortlessly pick up our brass with a magnet after shooting a
match stage. Coloring our cases means we can instantly separate
our brass from that of other competitors. Plus there’s that
unquantifiable “cool factor” of nonchalantly bringing something
interesting, useful and attention-getting to a match. Many
pistol competitors are also handloaders, so the other claims—did
I mention “40 reloadings” and “no trimming?”—are of eyebrow
raising interest to us.
Convenience and coolness aside, SST NAS3 may be the most
significant advance in cartridge case technology since brass
replaced the paper cartridge around 1870. Yes, steel, aluminum
and polymer are options for cartridge cases, but all are
“throwaway” technologies. Aluminum is too soft to safely reload;
the Berdan primers are there to discourage reloading. Polymer
cases get the same Berdan treatment for the same safety reason.
Steel cases are also universally Berdan primed and comparatively
difficult to work through dies, even if you are set up for
reloading with Berdan primers.
Which of SST’s claims for their new 9mm cases can we check for
ourselves? And which are really important to the handloader?
Let’s take ‘em by the numbers.
Stronger
Manufacturer tested at more than 65,000 psi—that’s almost 7.62
NATO proof load pressure—the NAS3 cases are incredibly strong.
SAAMI standard for 9mm is 35,000 psi; 9mm +P is 38,500 psi.
While we’re talking about this, let’s point out that though the
NAS3 case is plenty strong, handguns are not built to take rifle
cartridge pressures. The NAS3 case strength is no license for
handloading foolishness.
NAS3 case heads can be color anodized.
The NAS3 case is a nickel-stainless steel alloy cylinder crimped
to a nickel plated aluminum case head. Stainless steel does
indeed have a higher tensile strength than brass and so the case
material doesn’t “flow” forward on firing and eventually need
trimming, like a brass case, and it can withstand much higher
chamber pressures than brass. For the handloader, however, we
must redefine “stronger.” The crimped joint between the NAS3
two-piece case head and body is a weak point for handloading.
Though I just called the case body a “cylinder,” perhaps
“funnel” would be a more descriptive word. The base of the
stainless steel cylinder has a hollow tube extension that forms
the primer’s flash hole channel; the end protruding into the
case head is flared and crimped to bond the two pieces together.
Upon firing any cartridge, the chamber walls and the breech face
support the case; gas forces expand in all directions but of
course are directed by design to drive the bullet forward. There
is no force of consequence that pulls the cartridge case forward
on firing, so the NAS3 case/head crimp has no firing stresses
applied that would tend to pull that joint apart.
However, standard dies utilize the shellholder to pull the case
out of the resizing and expanding dies; the NAS3 case requires
use of special SST sizing and flaring dies that don’t stress the
crimp with that pulling action. The dies accomplish this by
pushing the case from the dies with a compressible synthetic rod
that acts like a spring.
During testing I found that pulling bullets will also overstress
that head-to-case-body crimp because inertia and press-mounted
bullet pullers apply force in that forward direction,
essentially pulling the head and case body in opposite
directions. Pulling bullets leaves a visible gap between the
case body and head, indicating the crimp is loosened and
necessitating discarding cases to avoid possible case head
separation upon firing or extraction.
I brought this matter up with SST spokesman Andrew Vallance. “In
the near future Shell Shock will be releasing a simple
attachment accessory to eliminate this issue and enable the use
of NAS3 cases with inertia pullers,” he said.
Life is full of trade-offs, so while we’re on the die subject
I’ll mention another caveat to accompany the special dies: even
though the SST resizing die has a carbide insert, the NAS3
stainless steel 9mm cases still require lubrication (though
brass cases do not).
Cheaper
MSRP for SST NAS3 cases is $60 for the first 500, 12¢ each, with
price reductions for larger quantities. An online check shows
new 9mm brass cases run from 14¢ to 17¢. Price advantage: NAS3.
Lighter
Yep. An average of 10 NAS3 cases weighed in at 29.7-grains each,
compared to a mixed batch of 10 brass cases at
58.8-grains—almost exactly half the weight of brass.
Resist corrosion
The stainless steel portion of the SST case is
corrosion-resistant.
My informal method comparing corrosion resistance to that of
brass was to leave a couple cases in a saltwater solution for
two weeks, expose them to the outside air for another two weeks,
then compare them to similarly treated brass. The NAS3
nickel-stainless steel case body survived just fine, but its
nickel plated aluminum case head corroded as much or more so
than brass. A claim refutation, it appears, but let’s have a
reality check: the test result satisfies curiosity but means
nothing in the real world unless you store your cases in a
saltwater solution.
More volume
SST claims two percent more case volume over brass due to the
squared bottoms at the case head versus brass having rounded
inside corners. The common method of measuring volume is to
weigh an empty case, then fill it with water and weigh it again.
Scales only promise a +/- .1-grain accuracy, so checking 9mm
case volume would be inconclusive unless you measured about 100
NAS3 cases and then 100 brass cases from each of several
manufacturers (after trimming all to the same length)—say, 400
cases total—and compared the results. Feel free, I’ve got a life
to attend to. I’ll concede this one to the manufacturer.
Consistent ignition
An extension from the steel case body crimps into the nickel
alloy case head to also form the primer flash hole.
This derives from beveling the flash hole from inside the case,
a well-recognized accurizing trick used in precision shooting
like NRA Long-Range and High Power competition. SST also
enlarges the flash hole, not for shot-to-shot consistency, but
helpful for reliable ignition when reloading with lead-free
primers for indoor shooting. The enlarged flash hole is possibly
desirable from a manufacturing standpoint, an aid perhaps in
crimping the body-to-case-head joint.
We can infer consistent ignition from chronograph extreme
spread/standard deviation (though other factors are also at
work), but independent testing by munitions specialist H.P.
White Laboratory has already done this work for us, finding
fantastically low standard deviations of 0.093 fps and extreme
spreads of only 3 fps with 124-grain FMJ bullets and 4.2-grain
of Titegroup.
+P velocity without +P pressure
Without access to a pressure measuring facility, we can’t verify
this with absolute confidence. However, we might make an
inference that would also infer some veracity for the two
percent volume claim above. We can load NAS3 and brass cases
identically and fire them; Boyles Law says that the NAS3’s
greater volume will result in lower pressure compared to brass
cases, which should result in lower velocity, and velocity we
can measure with a chronograph.
No trimming, 40 reloads
Pulling bullets overstresses the crimp, making cases
unreloadable.
The last two claims regarding case stretching and 40 reloads are
simple to check; though tedious and time consuming, they’re
worth the effort. For the sake of alacrity in presenting you the
SST case here and now, allow me some time (and pleasant weather)
to attend the range with calipers and loading press to see
whether we can get those 40 reloadings from a single case. Stay
tuned for a report with reloading and chronograph results in the
not-too-distant future. For now, let’s summarize the pros and
cons of SST’s cases for the handloader.
Pros
No case stretching—hence no trimming is necessary.
Flash hole beveling—an aid to uniform powder ignition and
hence accuracy—is factory applied.
Flash hole is enlarged for “lead-free” primers. While not
widely available to handloaders yet (only Fiocchi Zero Pollution
small pistol primers come to mind), we can expect more in the
future.
Lower initial cost than brass, plus reloading each case five
or 10 times more than brass cases is a significant saving.
Color coding bases for instant load ID.
Handloaders can get +P velocities without +P pressures.
L-Tech Enterprises loads its 124-grain Full-Stop bullet in the
SST case at nearly 1,200 fps and reports pressure below 38,500
psi.
Half the weight lightens our range bags, and we can sweep up
fired cases with a magnet. Plus there’s the simple “cool factor”
of unique-looking ammo, especially with color anodized case
heads.
Cons
Resizing cases requires lubrication. Adding this step back
into the handloading process negates one of the joys of clean,
rapid reloading on the progressive press with carbide dies.
Pulling bullets necessitates throwing away the weakened
cases.
Proprietary dies are required. Though any bullet seating die
will work, the unique sizing and flaring dies are available only
from SST, MSRP $99.99 for the pair.
New technology. As with anything new, there will be some
wrinkles to iron out, sure to be discovered by a base of
handloaders and shooters actually employing the technology over
time.
So, let’s load up and find whatever wrinkles might need ironing
…
The 9mm Luger is SST’s debut case—and more calibers, including
bottleneck rifle cases, are in the works. You can learn more
about SST at www.shellshocktech.com.
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