Category Archives: Weapons Technology

Even Glocks Can Break

even_glocks_breakAnybody recognize this little bit? If you run a Glock you probably do.

It’s the thumb button from what people trained on 1911s or other classic firearms tend to call a “slide release” and what Glock insists on calling a “slide stop.”

Why does Glock call it a “stop” and not a “release”? You’re looking at the reason. The cheap stamped part is not designed or manufactured to take the load of being used to release the slide. Official and canonical Glock practice is that you close the slide on a fresh mag by pulling it to the rear and letting it go — like a Luger or P.38, not guns that have Browning’s handy slide release. 

Of course, the slide release of a 1911 or BHP is machined from steel billet and heat-treated appropriately. JMB Himself intended you to mash your opposable thumb down on it to close the slide, because you needed your left hand to manage the reins of your cavalry mount anyway!

This image comes from Kyle Defoor’s Instagram, where he says:

Seeing some military and LE Glock 19 Gen 4 slide stop levers breaking more than a few times. Never seen this before so often.

A lot of his commenters are… well, we’re not willing to trade commenters with him, let’s just say that. But one of them had this observation, which gibes with what we’ve heard about Glock training.

I’m a factory certified Glock armorer and at my last recert they discussed their position that the slide stop is not a slide release and using it in this fashion can, over time, lead to failures.

And couple more had the sensible comments that,

If not a slide release why the ridges on face for grip?


It seems to me that it would get more abuse from going into slide lock than slipping out of the notch to send the slide foreword again. What am I missing?

To which the Glock armorer guy replied:

[T]hat’s a valid point and an acute observation. I am remiss in failing to ask my Glock rep, who was in my office just yesterday, for clarification on this.

OK, let us offer our own opinion (note, opinion) on this.

  1. In our opinion, the “don’t use it as a slide release” is a retrospective position that was created by the Glock organization ex post facto when someone broke a slide release. But the oldest official Glock documents we have on hand (a January, 1992 armorer’s manual, and a Glock G1 exploded view dated 1991) already refer to the part as a “slide stop lever.” (The part owners often call a “takedown catch” is, officially, a “slide lock,” not to be confused with the slide stop lever).
  2. Re: “why the ridges on face for grip?” On p. 14 of the 1992 armorer’s manual, it describes how to lock the slide back, and includes a picture. “[L]ock the slide open by pushing up on the slide stop lever while pulling the slide to the rear with the non-shooting hand.” (It then tells you to “Pull back slide to release slide stop lever and close action.” But it doesn’t warn you not to use the slide stop lever to release the slide).
  3. “Why does it break?” OK, here’s a couple pictures of Glock slide stops. First, here’s an OEM slide stop, photographed from the inside. glock-oem-slide-stop-insideNow, we didn’t have a handy photo of this from the outside, but this photo of a Vickers Tactical extended slide stop (we’ve got this part on our own Glock) shows what the other side looks like. glock-vickers-slide-stop-outsideCompare this to the failed stop at the top of this post.

We now have several clues as to why the stops are failing.

  1. People continue doing something the manufacturer says not to do.
  2. The slide stop is made from a single piece of sheet metal, stamped (“pressed” for Europeans) and folded to net shape.
  3. There is a small rounded notch, adjacent to the part of the stop that folds over to the inside, right where the part Kyle photographed began to fail (see where the failure crack is kind of gray at the top? That’s the oldest part of the failure. When it weakened the slide stop enough, the rest failed all at once — that’s the shiny part of the crack). The reason for the notch is to prevent a “stress riser” from causing the part to begin failing at this point, and it obviously is not working in 100% of use conditions.
  4. And that the problem just started showing up with greater frequency, suggests that some aspect of the manufacturing of the part may have been changed recently. Manufacturers are always making small changes in parts to improve something about them (often something that matters to the manufacture, like lower cost, or increase speed of manufacture, and doesn’t matter quite as directly to customers). Manufacturers also are known for making parts in-house and outsourcing other parts to subcontractors. These subs can change at any time.
  5. Putting thumb pressure on the slide stop stresses it several different ways. It can load it in torsion (twist), for which the engineers probably didn’t do the math on this part. It will definitely bend the part laterally (per the gun’s orientation). That stresses the outboard (left) side of the slide stop in tension, and the inboard (right) side in compression. Another way to think about it is when you bend a plate or bar, the side bent convex is loaded in tension, and the side bent concave is loaded in compression. Our best guess (and based on one picture of one part, it can be no more than a guess) is that this part began to fail from tension at the upper outboard corner of the slide stop.
  6. It’s a trivial physics or engineering problem to calculate the stresses on the part, but to know whether they exceeded the design strength of the part, we’d need to know the exact materials and heat-treating condition of the part.

A question on the Instagram page about whether this is happening primarily in high round-count guns isn’t answered, but round count doesn’t necessarily load the slide stop. A lot of cop guns are seldom fired, but are loaded and cleared at least once every shift. If they’re thumbing the slide stop a lot, they can bust their slide stop without even firing a shot.

One last thing: the failure of this actuating button end of the slide stop makes it impossible (or very difficult, requiring tools) to lock the slide back without an empty mag in the pistol. However, without the end of the stop, it looks to us like the basic running of the gun would still be OK, until you needed the slide stop to handle a malfunction. So in combat terms, this failure of the slide stop is fail safe.

So, What Use is TrackingPoint?

Here’s the deal that’s currently on. Tuesday they let us know that they’re down to 50 of them left, so they might be gone by now.

And here’s what it can do. Duel 1: 350 Yards, Off Hand, on a windy Texas day. Bruce Piatt is a National Champion — dude can shoot. But he gets one miss and one on the edge. (He’s using decent combat gear, including what looks like an FN carbine, and a 4×32 ACOG). Taya Kyle was at the time a novice shooter. She puts two in center of mass, using the Precision Guided Weapon.

Here’s a capability that you just don’t have without the PGM. Duel 2: Blind Shots, 200 Yards. Being able to engage the target without exposing yourself to enemy observation and fire is a completely novel thing. Sure, we’ve seen Talibs shoot at our guys like this, but these “Blind Shots” are aimed shots.

Yes, this is a completely unfair test, because it asks Bruce Piatt to do the impossible. With the ShotGlass, for Taya Kyle it’s possible.

Several of you have asked, why not spend the money on training and improve your skills? Bruce did that. He’s world-class good. (Yeah, soldiers and Marines shoot at this distance, but we’re shooting larger targets, and from a prone or foxhole supported position.

Taya didn’t do that, and yet, by exploiting the technology, she outshot Bruce. That is not to say Bruce’s skill acquisition was wasted time! After all, he’s lethal without all the gear. And he’d just be even better (more accurate and faster) if he was using the technology.

What use is Tracking Point? When we first started writing about it, we reminded you all of something Ben Franklin said. During his residence in Paris, one morning he was on his way to see an ascent of the pioneering French aeronauts, the Montgolfier brothers. And an intelligent lady, bemused by the American’s enthusiasm for this novel applied science, asked the great man, “What use is it?”

“My dear lady,” the prescient Philadelphian replied, “what use is a newborn baby?”

A century from now, weapons that don’t range and track targets for you, whether you’re a soldier or a hunter, will be nostalgia items, like muzzleloaders today.


Here’s the Shooter’s Calculator, a way to work your dope (at least initially) if you’re still doing the math somewhere other than inside your Tracking Point Precision Guided Weapon. Sent in by a reader who prefers to remain anonymous.

Update II:

If the embeds do not work (at least one Eurostani reports they are blocked at his location) then these raw HTML links to Vimeo might work.

If the raw links don’t work, we don’t know what to try next.

Book Review: Sporting Firearms: A Designers Notebook by Richard Florer

soorting-firearms-a-designers-notebookWe found this on Amazon and scanned the part of it that was visible online. We didn’t think it was valuable, lacking the sheet music (equations and other engineering data) of standard texts like Balleisen’s Principles of Firearms and the Rheinmetall Handbook, but then we thought — “If it’s no good, we should put a heads up on the Gun Design Books and Resources page.” And then we thought, “It would not be fair to write a critical review without reading the actual book. So we had better order it, and see.”

We’re very glad we did, because Sporting Firearms: A Designers Notebook is a good and useful book. Our mistake was in expecting it to be a mechanical engineer’s text book, like the indispensable Balleisen. But it is just what the title says: a designer’s notebook, full of the designer’s tips and tricks, and descriptive of his experiences in designing specific firearms.

The case studies in this book stem from Florer’s double-barreled capabilities: he’s a mechanical engineer and has worked as one in the industry (rising to chief engineer), but he’s also a practical gunsmith at home with the lathe and milling machine (not to mention a set of files).

One of the most interesting projects here is a redesign of the Weatherby Vanguard short-action mechanism (the same as the Howa mechanism, not the Weatherby Mark V) to take extra-long cartridges. Why would a designer want to do that? Bear in mind that these are hunting rifles, chambered for typical short-action cartridges like the .308 or 7mm-08. The SAAMI spec for cartridge overall length of the .308 is what has defined the length of the short action, so that you’re forever limited to bullets that are no longer than the 1951 descendant of World War vintage M2 ball that was loaded in the GI 7.62. But modern hunting bullets are longer, for both aerodynamic and penetrative reasons.

They must either be loaded deeper in the casing, robbing powder volume, or loaded only in long-action guns. But Florer devised a modification that lets one load 180 grain bullets in a .308 with the base of the cartridge seated exactly where it is on a 150 grain soft point. The modifications allow the loading of a cartridge with an overall length of around three inches, even a hair more, compared to the SAAMI spec of 2.81″ for the .308.

The modification requires increasing the bolt travel, and lengthening the magazine box 0.200″, both of which are practical on the Vanguard action. (The resulting rifle can accommodate longer handloads, but still works with factory loads. The chamber and headspace are untouched and unchanged).

sporting_firearms_contentsWe won’t, and most readers of this book won’t, ever hack a Vanguard for longer, heavier bullets, but the value of the book is in what it teaches about the thought processes that go into developing such a modification safely.

Another set of case studies involve development of unique necked .22 caliber wildcats, one for a rifle and one for a revolver.

A case that may be more broadly beneficial is a walk-through of the collaborative specifications development process for an unnamed firm’s new bolt-action hunting rifle. This is the framing device for Part I of the book (see contents at right), while Part II covers various specific projects..

Finally, there’s some ingenious mechanisms in here, including an adjustable tension (for accuracy) barrel forend bedding device, and several variations of set triggers, but, unfortunately, the technical details on these are sparse.

As sophisticated as firearm design is these days, publicly available information about it is still scant and scattered. Sporting Firearms: A Designer’s Handbook is a worthwhile addition to the canon.

Amazon link

Book publication press release (3 Jan 2013).

Deal Coming from TrackingPoint: 700-yard 5.56 AR

The TrackingPoint "Tag" button , here on one of their early bolt guns, locks the gun on target.

The TrackingPoint “Tag” button , here on one of their early bolt guns from three years ago, locks the gun on target.

If you’re already following the company by email (or perhaps other social media?) you are eligible for this. If not, maybe you can get to their site and get registered. (Tell ’em Hognose sent you). Here’s what Tracking Point founder and CEO John McHale sent us last week (emphases ours):

One year ago, TrackingPoint held the American Sniper Shootout pitting Taya Kyle against NRA World Shooting Champion Bruce Piatt. The shootout marked the re-launch of our business and I am pleased to report that thanks to you, TrackingPoint is resurgent and strong. On Monday, in celebration of this success and in celebration of the one year anniversary of the American Shootout, TrackingPoint is offering only to our current followers an Anniversary Edition M700 Sniper Kit. The M700 is a custom TrackingPoint gun built specifically for Taya to use during the American Sniper Shootout. The M700 is a unique semi-automatic 5.56 that has extended range out to 700 yards. 

Next week our newsletter will include the seven minute American Sniper Shootout Documentary and each day we will send you a unique out-take of specific shots taken during the competition. You will see extraordinarily challenging shots made under battle stress conditions including moving targets, off-hand shots, blind shots, and more.

If you guys would like, and we can pull it off technically, we’ll post these clips here. We’ll also notify you with all information about the M700 Sniper Kit that McHale lets us release. We have been strong supporters of TrackingPoint from the very beginning, through its near-death brush with bankruptcy organization, and we’re starting to see the emergence of some of the incredible capabilities that we always saw lurking in the future development of Tracking Point’s Precision Guided Munition technology.

We hope you enjoy the American Sniper Shootout videos and keep your eye-out for the Anniversary Edition M700 Sniper Kit. Once again thank you for your business and incredible support in bringing tremendous success to TrackingPoint.

If 700 yards won’t do it for you, or you’re a fan of the NATO cartridge, Tracking Point still has a few of the incredible M900 Limited Edition Kits available — $14k if you don’t add the Torrid thermal option. The kit includes the rifle, integrated scope, and has a 900-yard lock range and 20-mph target track velocity.


One downside to the TrackingPoint systems is that they are tuned to their proprietary ammo, and the ammo is very expensive — the 7.62 lists at nearly $3.50 a shot, in case (200-round) volume.

WWII British Gun Factory, “Night Shift,” 1942 (full) – YouTube

Let’s continue in the vein of production videos — here are Brits, mostly women, cranking out firearms to replace the piles left on the beach at Dunkirk.

Freely downloadable at the Internet Archive. “Shows a normal work night of workers, particularly women, at a British gun factory. Consists mostly of special-effect shots of factory equipment and personnel. The workers dance, sing, and eat lunch at 1:00 a.m. and have tea at 4:00 o’clock.” National Archives Identifier: 38643

via WWII British Gun Factory, “Night Shift,” 1942 (full) – YouTube.

It’s interesting to consider how primitive this factory is, compared to one in our modern day, 70-odd years later. And yet, this factory is gigantic overkill, if your standard of comparison is the minimum installation needed to manufacture effective arms.

Guns & Ammo Suppressor Magazine

Current Issue

Current Issue

While the major gun initiative likely to come from the incoming Trump administration is national concealed carry reciprocity (“like a driver’s license,” according to the President-Elect himself), and restoration of the self-defense rights stripped from soldiers and dependents by executive-branch action (these are likely to be restored the same way), industry watchers consider a delisting of suppressors from the National Firearms Act a third possibility. After all, suppressors have gone from known mainly for their use by Hollywood miscreants, to legalfor civilian ownership in 42 States, and in 40 of those states legal to use for hunting, also.

The American Suppressor Association (which finally gave up calling itself the Silencer Association) keeps track of these things, and the current map shows how suppressors are legal just about everywhere except highly urbanized states where criminals and their families are an important constituency, such as California, Illinois, New York, New Jersey and Massachusetts. Those states, where gun bans of all kinds remain popular, are unlikely to waive their restrictions.


Despite the holdout states, suppressors have become increasingly common as safety and comfort equipment, and the biggest single drag on the market is the ATF’s sluggish 1930s approval process.

Last Year's Issue. Note that this year's has more suppressors.

Last Year’s Issue. Note that this year’s has more suppressors — and they’re legal in one more state (and several more, for hunting)..

That makes this magazine special from Guns & Ammo extremely timely. It’s not their first one — they published an edition in 2015 (visible right), also — but this year’s, the yellow covered one seen at the top of this post, is a more complete and interesting one. We picked it up, of all places, at Walmart. If you can’t find it in Walmart, you can try ordering it direct from the publisher’s website for $8.99 (free shipping, presumably to the USA).

Here’s the editorial blurb from that website:

The second issue of Suppressor magazine is filled with reviews and roundups of the latest in suppressor trends. Josh Watson puts a roundup of .22 suppressors to the test, Kimberly Marie discusses why you don’t have to be an experienced shooter to use a suppressor and Sean Utley reviews several new offerings from SIG Sauer, Bell Precision, Thunder Beast Arms, SureFire, SilencerCo and more. You’ll also find a bolt vs. gas case study, an update from the American Suppressor Association and much more. Pick up your copy of 2016 Suppressor today!

The magazine has all the pros and cons of glossy gun magazines, with the pros including excellent, clear photography and punchy prose. The cons? Well, they’ll never say anything that might offend an advertiser. For example, an excellent technical article on the products of SIG’s “silencer division” is completely devoid of the interesting human story of how SIG developed the division by hiring Kevin Brittingham and his AAC team away from AAC after the company’s acquisition by Cerberus Capital’s Freedom Group (now Remington Outdoor). Is that because they don’t want to offend SIG’s Ron Cohen, Cerberus’s Stephen Feinberg, or burn any bridges with Brittingham’s quiet (pun intended) new firm, Q, LLC? We don’t know, but all the mentioned individuals (and the team members who have traipsed around following Kevin) are extremely interesting human stories that tie into the suppressor industry. (We hear from guys “in the community” that Feinberg in particular is “a great guy,” although the actual quotes tended toward more earthy soldiers’ and Marines’ language).

How is SIG going to keep innovating in suppressor design, when it’s in-house innovators checked out? You can bet that Cohen has a plan for that, but he hasn’t shared it with us, and there’s no sign that Sean Utley of G&A asked him.

On the other hand, Utley did get a lot of technical information about the SIG SRD-9 suppressor, and he understands the importance of some of the things that come in the box (like two boosters for tipping-barrel pistols, one with standard imperial threads and one with standard metric) and things that don’t (an adapter for fixed-barrel firearms, available as an option).

Utley also wrote an excellent article comparing four suppressors for the .338 Lapua Magnum, a round that can be fatiguing to shoot unsuppressed. (In our subjective opinion, it’s not as bad as the .300 Winchester Magnum in blast or recoil).

As always with magazine tests, the tests are brief and round counts low. That’s just the nature of the beast.

One suggestion that is made in a couple of the articles is that it’s probably best to try several suppressors before choosing one. This is, of course, impractical, given that it takes most of a year to transfer one, and is subject to punitive taxation under the NFA.

Suppressor delisting would not be a trivial undertaking, requiring Congress to amend a very old law. But as the existence of this magazine on a WalMart magazine rack illustrates, suppressors are increasingly part of the gun culture, and gun culture is increasingly part of the culture at large. Ergo, delisting is an inevitability; activism can simply fiddle with the timeline.

One article that novices should welcome is a very brief suppressor overview article for beginners by Kimberley Marie, that addresses why you should use suppressors, and why not, or, some of the pros and cons of these devices. Something like that belongs in every issue, but also an overview of how they work would allow authors of technical articles (like Utley) to assume a greater level of baseline knowledge.

And one article we’d like to see is a historical article per each issue. Probably not practical, given the limited editorial pages in a short publication. Fortunately, most of the ads are for other interesting suppressors, adding to the value of the magazine.

All i all, for $9, it’s a decent if incomplete survey of some of the most interesting (and most widely available) suppressors on the market today.

War Production: Propellers and Browning M2 .50s

They started with a factory that built refrigerators. But refrigerators is not what the War Production Board wanted Frigidaire to be making. So they converted one plant, and built new ones, including training new workers — many women — to replace drafted men.

The new products in Frigidaire’s Dayton, OH factories? Constant-speed propellers for training and combat aircraft, and Browning machine guns, mostly for the Air Corps.

The machine guns are mentioned near the beginning, in the context of the 250,000th Frigidaire M2 being produced on 22 June 1944, but after a long period of discussing propeller production, they go to the MG factory at approximately 9:42 in the video. Right after that, it shows an interesting test-fire cell for solenoid-fired MGs.

Frigidaire – These People – How a Frigidaire plant converts to Service goods production during 1940s.

via Frigidaire – For the Forces – Production During The 1940s – YouTube.

The technical information about the production of the guns is one aspect of this video, but what now seems like over-the-top patriotism is an interesting sociological aspect as well. We could use a little more of that can-do victory spirit, eh?

CZ Factory Promo & Tour Videos

After a very long and overly artistic 1-minute intro, this video (4:53) shows tantalizing glimpses of production in CZ today. One of the most interesting things is the injection molding of what appears to be wax patterns for casting pistol frames and many other parts. The patterns are only shown momentarily as ejector pins kick them out of the molds. Great stuff.

Here’s another production video, well narrated. (Duration 7:03). One thing you don’t often see is the laser bore sighting system that gets them most of the way to sighted-in without having to expend rounds. (They do, of course, expend rounds. Every CZ comes with a test target).

You may remember this video visit to the plant by Army Recognition website, which we’ve featured here in the past.

Welcome to a new week at We’ve got a lot of good stuff cued up for you, including something from our recent visit to New Orleans, some more manufacturing and smithing stuff, and a treat or two from the vault and/or footlocker. Life is good.

Wednesday Weapons Website of the Week: LaBounty Precision Reboring

labounty_precisionWhy would we make a Wednesday Weapons Website of the Week out of a single small shop’s web page? Well, it ties in to the discussion we’ve had on rifling machines and methods, which is, incidentally, the name of Clifford LaBounty’s book: Rifling Machines and Methods. For convenience’s sake, that’s the URL of the web page, too.

As far as we know, it is the only full-length book on rifling machines that makes an attempt to describe all the major methods, and it’s even more useful because it meets LaBounty’s intent in writing it: to pass on the information that nobody ever passed on to him, when he was starting out; to tell the barrel makers of the future what he wished somebody had told him.

So if you’re really interested in that stuff, do like we did, go to LaBounty Precision Reboring, and buy the book. It’s a ≅$50 8½ x 11″ paperback of about 170 pages, but, as he discovered when he started out, there’s not a lot of books on rifling out there. There is enough information on the book on the web page for you to figure out if you want it or not.

Apart from the book, he also has several other tools that are useful for gunsmiths seeking to accurize or blueprint bolt-action rifles, and a nifty holder for letter or number stamps that lets you mark firearms (or fixtures, or anything you mark with a stamp) in a neat, legible row.



Rifling Technology Videos

In keeping with our recent discussion of Rifling Methods, we thought we’d show you some variants of production rifling machines.

First, here’s how a modern small-to-medium sized-business does it — Krieger Barrels, which uses cut rifling, in a high tech way:

And now for old school, as in a century ago, cut rifling. Here’s a Pratt & Whitney sine bar hook-cutter cut rifling machine, restored. (Krieger, as you’ve just seen, also uses a similar P&W machie). This represents an example of World War I vintage technology, but can still produce accurate barrels. The single-point hook cutter was not replaced because the newer tech (in this case, mostly, broaching, a WWII vintage technology) could make barrels better. It could make barrels faster, an important benefit in wartime production.

The big oval structure above the bed of the machine is a marker of the Pratt and its foreign clones. The owner of this one comments:

This Sine bar hook cut rifling machine was originally owned by “old man Savage”. It then was bought from him by an Arizona gunsmith named Bill Sucalie. The diamond rifler, gundrill and gun barrel reamer was bought by Bill from Old man Savage all at the same time. Bob Blake my grandfather purchased Bill’s Gunsmith buisness in 1966 to where Bob and my father Dave Blake ran a Barrel Making shop for about 5 Years. We had kept the equipment all of these years and have remained gundrill speacialist ever since. We have now restored the rifling machine and here is the first barrel it has cut in over 40 years.