Category Archives: Weapons Technology

Wednesday Weapons Website of the Week: Just Fieldstrip

Just Fieldstrip is not exactly a website, but it’s a series of YouTube videos posted via check gun expert. As the name suggests, almost all of them are simply how to field strip quite a collection of historic, and sometimes rare and unusual, firearms.

The only audio is instrumental music, so they’re useful to speakers of any and no language alike. There’s a playlist of the series, but it hasn’t been updated in two plus years, and stops at #75. (We’ve found examples up to #90) There’s also a playlist of the series with no music and running narration — in Czech. Great if you have the right credentials (say, Defense Language Institute Basic Czech 1979-80, FLTCE Immersion Czech 1986) but maybe not so great if you don’t.

Here’s one that isn’t actually a field strip, simply an example of how to operate the Kolibri 2.7mm automatic pistol, which looks like a Baby Browning’s premature crack baby with the Browning 1900 fingered as Baby Daddy. (Was incest illegal in Liège early last century? Enquiring minds, etc. –Ed).

The Kolibri is Number 054 in the long-running series.

One of the more fiddly and complicated disassemblies is the fiddly and complicated Luigi Franchi SPAS-12, a bizarre shotgun that worked as a semi-auto and as a pump.

After the jump there’s a list of some, perhaps all to date, of the videos. Some we could only find in the Czech variant, some in the dubbed-music variant. Going through that list, we found one from a pistol we didn’t know, the Slovakian polymer-framed DA/SA Grand Power K-100, reported to be winning IPSC events in Europe. So we’ll close the front page out with a third video, the K-100 — Just Fieldstrip! (Interesting, the barrel rotates to look like an Obregon or some Berettas, but it strips like a PPK. We’ll have to look into this thing).

The author of these videos is associated in some manner with a Czech gun dealer, GunDrak.cz. The page is naturally in Czech. It has a video page that links to the Czech disassembly videos, too.

Click “more” to see the list of Just Fieldstrip / Rozborka a Sborka episodes we could find. (Unfortunately, not linked).

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Land Mines vs. Booby Traps vs. IEDs.

Those three are the most hated, if not always the most feared, enemy weapons. Much as WWII bomber crews loathed flak more than fighters (their gunners could shoot back at fighters!) the unattended (or command-detonated) explosive device is more loathed than direct fire. Tom Kratman nailed this in his military science-fiction novel, A Desert Called Peace, which we’re still reading.

“I don’t even like the idea of land mines,” Parilla muttered.

“No one does,” Carrera agreed. “Not until you have a horde of screaming motherfuckers coming to kill you and all that stands between their bayonets and you is a belt of land mines.”

How Armies Use Mines

In military usage, mines, which may be emplaced by combat troops or by specialist engineers, are used as artificial obstacles to hinder or channelize enemy forces, or as ambush initiators. It is good practice to initiate an ambush with the greatest casualty-producing weapon, or greatest shock-producing weapon, available to you, and the authoritative WHAM! of a Claymore is an excellent way to send a message to the enemy, when that message is: “Die, die, die!”

Note to national policymakers: If that’s not the message you’re trying to send as a matter of national policy, you may have selected the wrong tool when you chose the military as messenger.

In a well-executed ambush, the Claymore blast is followed by overwhelming firepower and then, very rapidly, by a lift and shift of fires from the objective to the enemy’s potential escape routes, while troops assault across the objective to ensure the total destruction of the target element, and to gather any intelligence that can readily be gained from their still-warm bodies and shattered equipment.

Just because enemy units are armored, there’s no reason not to initiate your ambush with a command-detonated mine. The Claymore has long had anti-tank equivalents in off-route AT mines, essentially a remote-command-launched rocket that you aim in advance where you expect the enemy armor to be. We don’t know how far these go back, but the first one we used to use was based on the old 3.5″ rocket launcher (the Super Bazooka invented in WWII and used in Korea after the 2.36″ one proved useless on T-34s). The US also has a set of shaped charges and platter mines that have a limited standoff capability. Most American troops never see or train with these devices; for whatever reason, they’re not a training priority, but they’re in the inventory.

The main use of mines, despite that long digression about ambushes, is to fortify positions. A minefield of this type has very limited utility if not covered by friendly observation and fire at all times; otherwise, the enemy can simply blow or lift the mines, something that, like mine emplacement, can be done “retail” by combat troops or “wholesale” by engineers. For this reason, the Hollywood trope of the patrol caught in the minefield is actually a very rare occurrence off-screen. You do not actually find your patrol in a minefield on a nice sunny day with the leisure to probe for mines with a stick (and please, not a bayonet). You find your patrol in the middle of the mines, usually a night in the foulest weather imaginable, and under accurate enemy direct or indirect fire.

In addition to mines that can be placed by troops, minefields can be emplaced hastily by engineer equipment, including sophisticated mechanical minelayers that lay mines in a ditch or holes the machines themselves dig, and pods that can scatter mines from aircraft, usually helicopters or (these days) UAVs.

Minefields emplaced by civilized troops for defensive purposes are, by international convention, marked with recognized international symbols. This is part of why mine, booby-trap, and IED warfare by irregular forces is often hated by regulars; the irregulars do not comply with these rules and norms, and so are thought to be fighting underhandedly. (The guerrillas, for their part, see it as merely doing what they can in an asymmetric fight).

The other part of forces’ loathing for enemies’ mine warfare is, as Tom’s character Duce Parilla seems to have internalized, you can’t fight back against a mine. The guy who killed or maimed your men is long gone. (Of course, you can fight back against minelayers, but the fight is indirect and requires you, too, to play to your asymmetric strengths). This feeling of frustration by mine-warfare attack (in this case, by booby traps that produced casualties) was a key ingredient, along with inadequate officer selection & training and bad leadership at all levels from corporal to Corps, in the misconduct of Americal Division troops that became known as the My Lai Massacre.  They were so tired of taking casualties by booby trap, and so badly led, that they took out their fear and frustration on enemy noncombatants instead.

As tragic as the outcome was for the simple peasant families of My Lai 4, the murders were a great victory for the Communists in the key center of gravity of the war — the minds of the American public and their elected leaders. It was part of an array of events that drove a schism between the military and the media that endures almost 40 years later.

So What’s the Difference?

Mines, Booby Traps, and Improvised Explosive Devices are three somewhat overlapping categories of (usually but not always) explosive weapons.

landmines_1

Mike Croll defines landmines as:

mass-produced, victim-operated, explosive traps.1

In American usage (Croll was a British soldier and, subsequently, NGO counter-mining expert), “landmines” also includes command-detonated weapons like the Claymore. It was once customary for patrols to use a Claymore wired with a tripwire and a pull or pull-release firing device to delay pursuit; this usage has been banned by American military lawyers who were, we are not making this up, inspired by Princess Diana.

Booby-traps are distinguished from mines by dint of not being made en masse in factories, but as Croll points out, “the difference can be academic,” and it’s certainly not significant to the victim. While no non-explosive victim-operated weapons are currently in production worldwide, non-explosive traps have been used since prehistoric times (Croll also traces the archaeology of caltrops and Roman obstacle fields in his book). In the early years of the Vietnam War, US forces did encounter Malayan Gates, punji pits, and other non-explosive mantraps; as the war ground on, the enemy improved his logistics and regularized his forces, and such bulky, hard to make, and easily detected traps gave way to explosive weapons.

landmines_2

Improvised Explosive Devices encompass everything that blows a fellow up, and that didn’t come out of the factory in the form in which it ultimately is used. The ED is often I from factory weapons that were not envisioned by their inventors as traps, command-detonated, or suicide mines. This definition of IED includes explosive booby traps, of course, as a subset. The many forms of suicide IED are also a subset; suicide weapons have approached mass-production status in Iraq and Iran, with such markers of production status as dedicated circuit boards.

We’ve provided a couple of Venn diagrams to help you sort ‘em out, but as Croll himself notes, there’s a considerable gray area. An AT mine can be fitted with a pull-release device or pressure plate and deployed as a massive overkill anti-personnel booby trap, for example. So perhaps instead of having solid borders, the circles should shade into one another.

But we’re with Parilla and Carrera. We hate ‘em, unless we’re behind ‘em and anticipating the banzai charge of the Third Shock Mongolian Horde.

Notes

1. Croll, p.ix.

Sources

Croll, Mike. The History of Landmines. Bromley, England: Leo Cooper, 1998.

The GunLab VG 1-5 Project Update

Chuck at GunLab reports on the ongoing VG 1-5 project. Pre-orders have been taken (cards not yet charged) and a list established at Allegheny Arsenal. It’s not cheap, but you’re not going to be the sixth AR in line at the range with this thing.

We’re going to catch you up on the last several VG 1-5 2015 updates, a couple of which we might have mentioned before.

Chuck had made the first few receiver reinforcement plates by hand on a finger brake. It worked but it was an ugly way of doing it, especially with hundreds of the guns spoken for by eager collectors. So he made a special pressing jig. Here it is in action:

The Magazine Release Button comprises a threaded insert riveted into a pressed dome, which is made itself from a flat laser-cut washer. Both processes are shown in the video below and explained with many photos in the appropriate GunLab post from back in January.

And so, finally, we get to the latest update, from 9 Mar 15, in which a test-mule VG 1-5 is test-fired. As Chuck writes:

We looked at everything from the barrel chamber and flutes to the firing pin length. We needed to check the recoil spring length and tension. Is the buffer spring too strong or weak? Will the fire control group work properly? All the drawings showed that everything should work but these are all questions that can only be answered during a test fire.

A problem is found, is rapidly troubleshot, and a new problem is found.

While the videos are a brief and on point, and have the advantage of motion, we strongly urge going to see the actual posts, because the many photos there and the descriptions reveal details not clarified in the videos.

We have every confidence that troubleshooting will be successful. How much confidence? Well, our VG 1-5 is on order.

There are several other cool things happening at GunLab, and they are worth checking out. (If you’re typing the address in, try to remember it’s gunlab.net. Someone has acquired the gunlab.com domain, but we don’t know who).

UPDATE

Sorry about the missing test-fire video. Should be fixed now.

Exotic Barrels Part 1: Squeeze Bores

In 99 repeating 9% of gun barrels, the caliber is what it is, and the bullet that comes out of the barrel is the same diameter it always was, just marked by the rifling. Likewise, the rifling twist is what it is, and from the point where is picks up in the leade (forward of the chamber) to the point where the bullet exits the barrel it is constant.

Then, there are the exotics, the ones that keep 99.9% from closing the gap between there and “all.” We’re going to talk about one exotic bore, and one exotic twist, in a pair of posts: Squeeze Bore and Gain Twist. Even though the names sound dreadfully like 1970s NATO codenames for Russian anti-aircraft radars, they’re both really a thing.

Squeeze Bore

The idea behind squeeze bore is to use the power of the powder to forge the projectile down in diameter. This would, in theory, do one of two things: blow the gun to Kingdom Come, or accelerate the projectile to velocities previously unheard of. It didn’t take long for people to try to reduce this theory to practice. The 1957 edition of Naval Ordnance and Gunnery, Volume 1:  Naval Ordnance, a training manual coded NavPers 10797-A, showed five different ways to get high velocities. The first is the familiar expedient of a lighter projectile, and the second, the saboted projectile used in most tank KE rounds these days, and in the .50 SLAP (saboted light armor penetrator) round. The third example, essentially beefing the gun up to take excessive pressures, doesn’t seem very practical, and the fifth was, in 1957, science-fiction stuff but is now a pretty routine way to get longer ranges in artillery. Which leaves the fourth example, D, our squeeze-bore

CHAPTER-6-E-FIGURE6E1-PAGE-95

A very, very gradual and subtle version of squeeze bore is the choke used on some firearms. But there’s nothing subtle about true squeeze bore. The World War II German Pak 41 fired a Gerlich-designed 42mm projectile, which the barrel squeezed down to 30mm at the muzzle. At around the same time, the US developed (at Frankford Arsenal) squeeze bore M2HB barrels, which fired a special bullet that squeezed down from .50 to .30 caliber. These guns produced extremely high velocities, with kinetic energy and penetration to match.

S.PzB.41 in action (or at least, being demonstrated). Wheles were removable to lower silhouette.

S.PzB.41 in action (or at least, being demonstrated). Wheels were removable to lower silhouette. Troops show scale… this is really small for something that can ding a JS-1’s frontal armor.

Squeeze bore was primarily used experimentally in antitank weaponry. The one weapon fielded with a squeeze bore was the German Gerlich S.PzB 41. The name Schwere Panzerbüchse meant, literally, heavy anti-tank rifle, and the Germans may have seen it as a replacement for the 7.92 x 94mm PzB 39, but its lightest variant weighed around 300 lbs. It could be broken down into smaller, man-portable-for-a-short-distance, loads.

Factory photo of the stripped-down paratroop version.

Factory photo of the stripped-down paratroop version.

The effect can be approximated by firing an oversize cartridge in a smaller-caliber bore, if the throat or leade is not too tight. (If it is, you get a kB! instead). You’re more likely to get away with such an inadvertent bore squeeze if the projectile is highly malleable, like a soft lead bullet. The Gerlich system used a tungsten penetrator with an aluminum alloy jacket, including crushable skirts. The projectiles looked like this (HE/frag on the left, with a filler of phlegmatized PETN;  AP with a tungsten-carbide penetrator on the right):

28-20 squeeze bore

(source)

The S. PzB. 41 was very effective; at close range it could penetrate all mainstream Allied armor (even the KV-1 and JS-1 tanks), although its behind-armor effect was limited. The Germans were successful in making squeeze bores where other nations’ designers had failed. They mounted it on SdKfz.250 half-tracks and used it as a trailered, man-packed and airborne weapon.

A larger squeeze-bore, the Pak 41, was deployed in small numbers. The ammunition closely resembles the 28/20mm of the S.PzB.41 but is much larger: it started off at 75mm and squeezed down to 55mm. An intermediate sized version was a 4.2 cm (42mm tapering to 28mm) squeeze-bore version of the familiar Krupp 3.7cm light anti-tank gun. (German guns are described in centimeters — move the decimal point once for mm — and their squeeze-bores are known by their initial, not squeezed, caliber).

Pak 41 APBCT

Making a tapered or “squeezing” rifled bore is a challenge, if you think about it, and conventional methods of rifling such as buttons and broaches don’t adapt well to it. (Cut rifling does adapt, but at a price in complexity. But the German invention of hammer-forging barrels over a mandrel opened up mass production to squeeze bore in German plants. (A microscopic amount of taper is usually used in hammer forging, to facilitate mandrel removal. But the amount of taper in a squeeze bore is much greater).

The British made a theoretically sound and plausible attempt to work around the difficulty of drilling and rifling squeeze bores. This was a squeeze-bore muzzle attachment called the Littlejohn for the 2-pdr antitank and light-tank gun, in order to give some realistic anti-tank capability to the airborne (glider-delivered) Tetrarch light tank and various wheeled AFVs.

Littlejohn_Adaptor_Bovington

It squeezed the round after it had been spun to speed; the holes you can see were for pressure release. The Littlejohn was conceived by a Czech emigré, Frantisek Janacek (whose name means “little John”, literally) and was made for the 40mm Vickers S gun as well as for the 2-pdr. The ammunition featured a tungsten penetrator and aluminum carrier, must like  the German squeeze-bore ammo. The US also experimented with Littlejohn type adapters and projectiles, and discovered that firing the Littlejohn projectile from the gun without the adapter produced equivalent velocity improvements without compromising the ability to fire  ordinary projectiles. (In effect, this was using the lightweight projectile as in Illustration A at the top of this post, rather than a squeeze-bore as in Illustration D).

langsford_extruder_bulletsFor a while, there was a squeeze bore gun that anyone could buy. Australian gunsmith Arthur Langsford, an expert in rimfire rifles, used an extended leade or forcing cone to make rimfire guns that fired an ordinary .22 LR round and produced a high-velocity .20 or .17 elongated slug. The rifling didn’t begin until after the forcing cone. They seemed to work well, but didn’t catch on, and pressure and velocity deltas between various brands and kinds of rimfire ammunition were probably larger than anything SAAMI would ever tolerate. The Myra “Extruders” Langsford made are curiosities today.

In the end, squeeze bores were a possible tank solution at one moment in time, but their performance has been overshadowed by accurate fin-stabilized discarding sabot heavy penetrators, fired (usually) from smooth-bore guns.

Next, Gain Twist, an old idea that’s making a comeback.

Sources

Department of the Navy. Naval Ordnance and Gunnery, Volume 1: Naval Ordnance .NavPers 10797-A.  Retrieved from: http://www.eugeneleeslover.com/US-NAVY-BOOKS/1-NO-10797-A-NAVAL-ORDNANCE-AND-GUNNERY.html

Langsford’s Squeeze-Bore Rimfires.Is this Near-Forgotten Idea Too Good to Die? Guns Magazine, January 2011. pp. 18-19. Retrievable from: http://fmgpublications.ipaperus.com/FMGPublications/GUNS/GUNS0111/?page=18

(Others as linked. List not completed due to time limits).

Napoleon III was a Weapons Man

portrait_de_napoleon_iiiWell, OK. A Heavy Weapons man, perhaps — an artillerist who once sat down, while imprisoned, to  write an engaging and technical, five-volume history of artillery, with a title as comprehensive as his intent: The Past and Future of Artillery. Remembered today for little more than his army being pantsed in the Franco-Prussian War in 1870, Louis Napoleon was a remarkable, erudite, and intelligent fellow. When you marvel, today, at the beauty of Paris you’re marveling mostly at the nephew’s makeover of his capital city, not the works of his uncle or of the Bourbon dynasty (although Louis was careful to preserve the best of what came before). Those big “N” monograms on the bridges of the Seine? Not the victor of Borodino (pyrrhic though that victory was) and Austerlitz, and the vanquished of Waterloo; the nephew, who was captured with his army in a German encirclement, to the chagrin of all Frenchmen then and now.

Napoleon III also created the long-standing Legion d’Honneur, funding its stipends to recognized soldiers with money derived from the expropriation of the family of the Duc d’Orleans. (In 19th Century France, politics remained a contact sport).

Unfortunately for those of us who would read his whole treatise on artillery, Louis-Napoleon Bonaparte, as he was known at the time, did get relief from his prison stint in the 1840s and turned to the matters of state which would one day seat him on an imperial throne. He never seems to have resumed work on The Past and Future of Artillery, of which only the first volume was published.

napoleon-iii-at-paris-1867-granger

While we’re attempting to find an digital copy of the English edition of this volume (hell, we’d take in en français, and does anybody know if any of his notes and illustrations for the subsequent volumes survive?), we can offer the preface to you.

There are some remarkable insights in this short preface. For example:

Inventions born before the time remain useless until the level of common intellects rises to comprehend them. Of what advantage could a quicker and stronger powder therefore be, when the common metal in use was not capable of resisting its action ? Of what use were hollow balls, until their employ was made easy and safe, and their explosion certain ? Or what could the rebounding range, proposed by Italian engineers in the sixteenth century, and since employed with much success by Vauban, avail, when fortification offered fewer rebounding lines than now ? How could attacks by horse-artillery, attempted in the sixteenth century, succeed, when the effects of rapidity in the movement of troops on the field of battle was so little known that the cavalry always charged at a trot ?

There is a mutual combination which forces our inventions to lean on and, in some measure, wait for each other. An idea suggests itself, remains problematical for years, even for centuries, until successive modifications qualify it for admission into the domain of real life. It is not uninteresting to trace, that powder was probably used in fireworks several centuries
before its propelling power was known, and that then some time elapsed before its application became easy or general.

Civilization never progresses by leaps, it advances on its path more or loss quickly, but regularly and gradually. There is a propagation in ideas as in men, and human progress has
a genealogy which can be traced through centuries like the forgotten sources of giant rivers.

For a man who is commonly and popularly dismissed as one of the least brilliant of the crowned heads of old Europe, those are some remarkably insightful lines.

Or consider this excerpt:

Fire-arms, like everything pertaining to humanity, did not spring up in a day. Its infancy lasted a century, and during that period it was used together with the ancient shooting instruments, over which it sometimes was victorious, but by which it was more frequently defeated.

The Preface alone makes it crystal clear that Napoleon III was a comrehensive student of artillery and arms, and the history of them; and that his lack of completion of The Past and Future of Artillery is a very great loss to all students of weapons.

Napoleon III on Artillery OCR.pdf

Bubba Got a Boring Bar

bubbas boring bar AR

This is weight savings the hard way, considering that most of what’s cut away is 7075 or 6061 aluminum. You just can’t save that much weight that way.

CubanFALThere are FALs kicking around Latin America and Africa with a big borehole like that in the magazine well — that’s because they were supplied clandestinely by Cuba, and los Pollos Cubanos used the boring bar (or maybe a fly cutter, we defer to the machinists in the audience) to remove the Batistiano Cuban crest in hopes of concealing the guns’ origin. (Lotsa luck. Western intel agencies had the manifests of the deliveries, by serial number).

We found the Swiss-Cheese-AR image here, linked from here, hat tip Nathan S at TFB.

Aero Precision has gotten into the game with some gimmicky skeletonized lowers. This is not a production item, but was an experiment:

Aero Precision SkeletorThat’s also thanks to TFB. Structurally, it might hold up or it might not (really, most of the material in the sides of the lower is there to provide dust seal, and, to a limited extent, a shear web, so there’s no reason skeletonizing shouldn’t work, structurally). But the total weight savings is nominal: 0.169 lb or about 2.7 ounces. (About 0.08 Kg for those of you who roll that way). They could probably have saved almost as much by milling off the A2 reinforcements to the pivot pin lugs and buffer tower areas.

That gives you an idea of what Bubba’s Boring Bar Blaster actually saved: less than 2.7 oz, to be sure. That’s winning the game the hard way.

Aero Precision is not alone. Daytona Defense & Tactical sells a skeletonized “Reaper” lower for $85 bare and $90 anodized black. It looks like they took many of the same cuts Aero Precision did (we’re not going to guess who was first).

Daytona Defense Reaper

So what’s the game? As you might guess from all the discussion of weight, The Lightest AR Going. There’s a Tumblr where a guy aimed for 60 ounces (he overshot but not by much), and there are several other competitors around. So a new guy’s aiming below 60 ounces. Of course, his definition of a “fully-functional AR” may not gibe with yours — one of the first parts he sacrificed was the bolt catch, shortly followed by the magazine catch (he’s making a fixed-mag 10-round firearm). And we’ve got our doubts about the long-term viability of his aluminum bolt carrier (yes, really). But even he has said, he’s not drilling the thing full of holes.

It might be that X Products got the whole Gun of Skeletor thing started by, after a skeletonized drum magazine caught the public’s eye at SHOT, making a run of the things. (Not a short run, either. For 2015 they made 1200 Skeletonized mags for SR-25 pattern .308s, and sold ‘em out). The silhouette of the skeletonized AR-15 drum has been used as a sort of trademark by the company ever since.

Hey, you want a light AR? Going to shoot it with irons? Get an old Colt SP1carbine. Yes, it will have some compromises: iron sights only, of the less precise (and slightly harder to adjust) A1 flavor. No rails or freefloated goodies. But it’s only 6 pounds and change. If you want to get to 4 pounds and below, you can only do it by accepting unpleasant recoil, shorter life, and compromised performance.

If that’s a good deal to you, or if you just want to experiment, have at it.

 

3D Printed Fire Control Group

We’ve seen several of the WarFairy designed 3D-printed AR lowers being put through their paces, but here’s something we weren’t expecting to achieve test-fire status so soon — the Deimos 3D-printed fire control group.

The printer used was a Rostock Max V2, a deltabot style printer. An E3D hotend was used. The material was ABS filament and was treated with acetone vapor after printing. The same printer printed the lower receiver (which had mods to accept this FCG) and the FCG itself.

The FCG design is based on general best practices, adapted for 3D printing and for ABS plastic as a material. Before it is manufactured, it is rendered, both bare:

Deimos FCG rendering no receiver

And in a rendering of the lower receiver:

Deimos FCG rendering

By “general best practices,” we mean a trigger with hook or hooks, hammer (with places for the hooks to engage) and disconnector (also with hook) of the type designed by Browning over 100 years ago for such semi-auto firearms as the Auto 5 shotgun and the Remington Model 8 rifle. This general Browning design was adapted by Garand, Kalashnikov, Stoner and many other subsequent designers. (If you examine an AK and AR closely, you’ll see their kinship in this area. Both inherited the Browning fire control, the AR via Garand and the AK via Remington Model 8). This FCG has three parts in semi-auto form: a trigger, a hammer, and a disconnector.

Deimos FCG parts w springs

By”‘adapted for 3D printing and ABS plastic” we refer to changes required by this material and means of manufacture. Each of the parts is printed on the Rostock Max before getting its acetone vapor bath. And each part has some base and support material that must be removed.

Deimos FCG disconnector as printed

ABS is a strong plastic, but a brittle one. Nylon may be better; an FCG printed in white nylon (presumably Taulman 618) is shown here. It’s unknown why this version has not been given the test-fire treatment, yet; perhaps there are yet undisclosed problems with it. But the nylon works better “on paper.”

Deimos FCG nylon

Here’s the FCG in the lower, cocked:

Deimos FCG in place

And here it is, decocked:

Deimos FCG in place hammer down

The “wet look” of the plastic is a result of the acetone-vapor bath.

Home manufacturing is just getting started, and right now, it’s still for tinkerers and fiddlers, not for end users. It’s a bit like computers were in the early years — it’s in the hands of a shadowy priesthood, guardians of abstruse knowledge. But it turns out the priests are very friendly and helpful once you show a sincere interest.

It’s still harder than (and easier to go wrong with), say, starting up a new Mac or assembling an Ikea table. But so were earlier versions of the same products.

Some people will try to stop this. Lotsa luck. You can’t stop the signal.

This isn’t just about one single design for an AR fire control group. It’s about putting the tools of design, testing, and iteration — the whole RDT&E cycle, really — into the hands of anyone who’s got the nerve to pick them up.

John Browning had to file metal into shape, largely by hand, to transfer his ideas into real prototype firearms. But that was a century ago. Today, we don’t have to any more.

Latest Printed AR Lower Test Fire

This is a more recent AR lower design, called the Alimanu Phobos. Here’s an image of it:

alimanu_phobos_printed_lower

And here’s the source of that image, a video showing the lower and showing it being test-fired.

Here’s what the video post says:

A test-fire video of the Aliamanu-Phobos AR-15 Lower Receiver designed and printed by ArmaDelite. Printed with ABS plastic on a XYZPrinting da Vinci 1.0 printer, this design is derived from previous designs like the FOSSCAD Phobos, Vanguard and vanguard JT lower receivers. MOAR test fire videos coming soon!

We suspect that the feeding problems may be due to the reduced rigidity of the lower compared to a standard 7075 machined forging. If the positioning of the magazine with reference to the bolt carrier is not consistent, you might get results like this.

The files can be found here:

https://www.sendspace.com/file/lkw9nm

Don’t click any of the big Download buttons. This is what the actual link will look like.

Screenshot 2015-02-22 01.12.36

Annoy a totalitarian. Share gun design files.

 

Additive Manufacturing in Defense and Aerospace

Today, we have two links for you that will expand your knowledge of what the DOD and Aerospace world is doing with additive manufacturing.

Additive Manufacturing for Armaments

Screenshot 2015-02-19 22.56.11The first is slightly dated, because it comes from the NDIA’s 2013 Armament conference. (Yes, 2013 was a long time ago in this rapidly developing field). It is the presentation slides of Stratasys’s John Dobstetter. Stratasys (SSYS) is one of the two large publicly traded firms in the field (the other is 3D Systems, whose ticker symbol fits: DDD).

Personally, we wouldn’t cross the street to whiz on Stratasys if they were on fire, because the company is firmly antigun and pro-gun-control, but Dobstetter’s presentation is an excellent one that starts out assuming that (1) his audience knows nothing about additive, but (2) it’s a bunch of smart people who know manufacturing and catch on quickly.

Screenshot 2015-02-19 22.56.28There’s fascinating stuff about when to use additive (see the Sweet Spot slide above) and how it can be applied to every phase or stage of manufacture (see the Lifecycle Applications slide to the right). Switched-on manufacturers, like Czech airplane manufacture Evektor, are using additive parts both as tooling and as end use parts.

There are some extremely clever uses of additive, either alone or hybridized with other tools, for composite layup tooling, producing some very interesting carbon, glass and aramid (Kevlar) parts. Likewise, end uses can be hybridized, with additive-manufactured complex ends added to shafts or beams made by winding filament or tow around a simple metal mandrel.

A .pdf of Dobstetter’s presentation is found here in the archives of the 2013 Armament conference.

Additive Manufacturing for Aerospace

MIT Technology Review has an interesting article (aren’t they all? Well, in MIT Tech Review, maybe) called Additive Manufacturing Is Reshaping Aviation. In this case, they’re not talking about little piston-plane builders like Evektor or Cirrus, but the big gorillas of jet-engine production, Pratt & Whitney and GE.

prattwhitneyx299Pratt & Whitney already uses two additive manufacturing techniques to make some engine components. Instead of casting metal in a mold, the methods involve forming solid objects by partially melting a metal powder with either a laser or an electron beam.

Additive manufacturing processes can reduce waste, speed up production, and enable designs that might not be feasible with conventional production processes.

Ding ding ding… we have frequently mentioned this benefit, the ability to design things free of the shackles of traditional subtractive manufacturing.

The novel shapes and unusual material properties the technology makes possible—such as propeller blades optimized for strength at one end and flexibility at the other—could change the way airplanes are designed.

Of course, propeller blades are already optimized that way, by having taper in three dimensions. And a company named Carter Aviation Technologies has developed revolutionary propellers that use a flexible composite skin around two spars that flex like the bones in your forearm to change the delta of pitch in the propeller, whereas conventional propellers can only change the pitch itself, not its rate of change. (Hey, you could use the additive tooling that Dobstetter showed in the first cite to make all the iterations of a Carter-patent propeller that you could possibly use).

Meanwhile, engineers hold out hope for today’s amazing technology to be supplanted by better machinery — finer resolution, faster printing, better-understood statics & mechanics. Even as great as the state of the art is, the engineers must push it:

…additive manufacturing techniques need to improve to allow for higher precision. Once researchers understand the fine, molecular-scale physics of how lasers and electron beams interact with powders, [P&W engineer Frank Prelli] says, “that will lead to the ability to put in finer and finer features, and faster and faster deposition rates.”

Whatever happens with the jet engine makers and the airframers that are their major customers, we can expect more and better from additive manufacturing. While the whole thrust of the article is aerospace, it has clear applications to defense and firearms manufacturing.

And A Bonus from MIT Tech Review: Nanosteel

What happens to steel when you apply nanotechnology to it?

MIT Tech Review’s Kevin Bullis (same guy that wrote the additive article linked above) is saying things that scarcely seem possible:

An inexpensive new process can increase the strength of metals such as steel by as much as 10 times…

Can you think of a firearms application for that? Or about 100 of them? We sure can. (Saving 90% of the weight of a Browning MG in .338 LM?)

But wait! It turns out it doesn’t just strengthen the steel… it also makes it much more corrosion-resistant. It works by electroplating nanometer-thing material onto a part in nano-engineered layers. It has the effect of changing the apparent properties of the now-hybridized part.

And it’s not significantly more expensive than current plating and coating processes.

Developments in Steel Armor

Some time ago we covered the types of Armor available to vehicle designers through World War II and explained why penetration of Rolled Homogeneous Armor, then state-of-the-art, is still routinely used as a standard measuring stick for armor penetration. But while RHA was the tank skin of choice in 1945 (with cast armor used for specific purposes, and face- (aka flame-) hardened armor on the way out), armor developments didn’t stand still then.

By the 1970s, British research had produced composite armors that were more effective, especially against Monroe effect shaped charges, than RHA. The British armor and its American derivatives (British government researchers shared their discoveries freely with US Army engineers and contractors on the M1 Tank and M2 Bradley contracts) were developed under conditions of great secrecy and remain, in detail, classified. You can find generalities about how they work online and in specialty books.

But the development even of steel armor did not stop with RHA. Since the end of World War II, steel makers and AFV engineers have pursued harder armors, called in English High Hardness Armor (HHA) and Dual Hardness Armor. These armors are challenging to produce, because increasing armor hardness risks embrittlement of the metal. Recently, a Swedish steelmaker has gone further in developing Ultra High Hardness Armor (UHH).

HHA is described by the military standard MIL-DTL-46100E, and offers a hardness range of 477–534 Brinell hardness number (BHN).

DHA is described by the military standard MIL-A-46099C. DHA is produced by roll bonding a 601–712 BHN front plate to a 461–534 BHN back plate; this gives the armor an extremely hard layer bonded to a hard-but-tougher layer. (That is, of course, reminiscent of WWI and early WWII face-hardened armor, where a more ductile, less hard, metal panel would be hardened to 500-700 BHN, but just a few millimeters deep). By fusing two different hardnesses of steel into a single plate, they produce a heterogeneous armor plate with both the ability to resist penetration by a hit (which comes from hardness) but also, without cracking (which comes from ductility).

UHH describes monolithic (probably. homogeneous) armor plate of greater than 600 BHN. The Swedish firm, SSAB Oxelosund AB, has developed two commercial grades of UHH, one, Armox 600T, offering Brinell 600 hardness, and an even harder plate called Armox 600 Advance offering an extrapolated BHN of over 650. (For those of you comfortable with the Rockwell hardness scale, Armox 600 Advance equates to RC 58-63. The armor production process for Armox seems, to the limited extent the Swedes have released it, conventional.

ssab_hha_armor_production

Despite their conventional-appearing production process, these armors are remarkable. To achieve penetration half the time, of 8mm (!) of Armox 600 Advance set at a 30º angle, a .30 caliber AP projectile must be traveling ~860 m/s — which is faster than the muzzle velocity of most .30 firearms (a 7.62 x 54 mm PKM is about 820-825 m/s). It protects against a .50, half the time, to about fps; to protect against .50 AP to 820 fps you need to step up to 12mm (.465″) plate. These are WWI tank and WWII light-tank thicknesses of armor, with much better defensive performance than the RHA and FHA of that period.

7mm Armox 600T stopped 4 of 7 .30 rounds.

7mm Armox 600T stopped 4 of 7 .30 rounds from any penetration, and the other three’s penrtration was nugatory.

 

Another way of taking a broad view of the performance of UHH is that across the board, there is an advantage of about 120 m/s or 400 fps difference in the velocity of impact that this armor will shrug off, vs. the MIL-STD for HHA.

Cal. .50 AP had its way with 8mm 600T -- half the time.

Cal. .50 AP had its way with 8mm 600T — half the time.

There is an excellent report from 2008 on DTIC (clicking downloads .pdf) on the evaluation of Armox 600T and Armox Advance, Ballistic Testing of SSAB Ultra-High-Hardness Steel for Armor Applications. The purpose of this evaluation was to help set up a MIL-STD for Ultra High Hardness Armor; one outcome of that is the detail standard, MIL-DTL-32332 (MR) 24 July 2009. Detail Specification: Armor Plate, Steel, Wrought, Ultra-High-Hardness (link to everyspec.com).

Note spalling on Armox Advance. It was also somewhat prone to cracking, if the edges of the plate weren't properly dressed.

Note spalling on Armox Advance, which would create secondary fragmentation in an armored vehicle. Advance was also somewhat prone to cracking, if the edges of the plate weren’t properly dressed.