Category Archives: Weapons Technology

Guy in a Garage Gets Quiet… in 5.56 and 7.62 (.300 BLK)

(Yes, 80s-90s era SF’ers, the “5.56 and 7.62” is a Blank Frank Toney reference. For the rest of you, on with the story). Our good friend Guy in a Garage (hereafter Guy) has been up to all kinds of good. You may recall that some time ago he applied to the ATF to manufacture suppressors on ATF Form 1.

He didn’t go about it by half measures. Here’s his 5.56mm suppressor, showing 3D design, computer finite element analysis of the projected flows, and parts machined, mostly, from 7075 round bar stock. The tube is Ti alloy. There’s a large chamber, followed by a blast baffle.

giag-suppressor-internal-2While the baffles are generally made of aluminum, the blast baffle is 416 stainless. Guy says:

This took a lot of work and I’m glad everything came out so well. I knew from the start that I aluminum wasn’t going to hold up to 5.56. I also knew that excessive backpressure could cause some issues in this short of a barrel. My design is based on the AAC M4-2000. It has a large expansion chamber, one blast baffle, and several clipped cones spaced closely together. This blast baffle does a lot to keep backpressure reasonable. I milled it from 416 stainless.

Here’s the 3D design of the blast baffle:giag-suppressor-part-2

The regular baffles. These are very reminiscent of some baffles Gemtech uses, as discussed below.giag-suppressor-part-3 Here’s the FEA of the baffle, showing the projected pressure drop across it. Noise suppression is all about managing pressure, temperature and time. (Software: Autodesk Flow Design, which is free as in beer).giag-suppressor-flow-sim-2

And here’s similar beauty shots of his .300 Blackout suppressor.

giag-suppressor giag-suppressor-baffle

A look in at that type of baffle. That’s not a baffle strike, that’s a feature of the design:


And here are the pair of them, completed and installed:


There are some other Guy in a Garage features there, including a home-made lower and home-made thermal sight. He used a quick-detach system designed by Yankee Hill Machine.

A suppressor (or any muzzle device) made of aluminum alloy, even a strong one like 7075, is going to have durability issues relative to one made of steel or exotic material like cobalt alloys (Inconel) or titanium alloys. But the exotic metals are much harder to machine than steel. This is one reason that selective laser sintering has been cost-effective for prototyping and limited production in such exotics. If you’re limited to subtractive manufacturing, aluminum alloys and steels are much more easily cut.

A word on baffles. We just got to try out a Walther .22 with a Gemtech suppressor that uses a similar style baffle. The suppressor was Hollywood tiny, but with subsonic ammo it was graveyard quiet. In fact, close to Hollywood quiet. (You do know the sounds of “suppressed” firearms in movies are dubbed in in post-processing by the Foley artists, right?) It made our old Hi-Standards sound like a 2″ .44 Magnum by comparison. We didn’t try the pistol with supersonic ammo, but the guy who had the Gemtech (his organization’s, we think, not personal) says it’s still extremely quiet, just not that quiet.

In the Gemtech, the little notch that looks to the novice eye like an artifact of a baffle strike — it isn’t — is turned 90º from the one in the preceding baffle. The Gemtech’s baffles are made of titanium, one reason the suppressor is as light as it is small.


We should have initially included these, in which Guy (username Flood_) answers many questions: Imgur thread and Reddit thread, both from three weeks or so ago. Don’t forget to click the “More comments” button at Reddit.

Ghost Gunner Tips & Tricks #2: Setting up a GG Station

This is a follow-up to our previous post on this general subject, which was cleverly titled Ghost Gunner Tips & Tricks #1This post is the second in what we expect to be an ongoing series.

We have the GG sitting on a rolling tool cart. Here is what is good and bad about that.


  • Good: it’s easily rolled around, and plugged into the gunsmithing workshop computer, or disconnected and rolled out of the way, because the same computer is also used as the book scanning computer and station with the Fujitsu SV600 scanner. It provides a single location for the machine and its ancillary stuff from USB cable to jigs and fixtures and some manuals and instructions. We can even keep workpieces waiting to be run in one of the drawers.
  • Bad: The GG generates a good bit of force when its axes are running, and so it has a tendency to make the base move. But if you lock the locking casters of the tool cart, it actually walks on the rubber mat atop the cart. We’re thinking a thick pad from Tractor Supply will put this to a stop, but we fear the moving cart will have an effect on finish quality,

The cart itself is a WorkSmart model that we bought, on sale, from MSC Direct. We have tool boxes from Craftsman Professional, Snap-On, Craftsman (import), and other makers as well. You may have noticed that there is a wide range of prices for what superficially seem to be very similar boxes. In our experience, the difference between them comes down to several things, all of which favor the name-brand box over the cheap Chinese stuff.

  1. The better the box, ceteris paribus, the thicker gage the metal is.
  2. The better the box, the better the drawer slides are.
  3. The better the box, the more readily repairable it is and the more available spares are.
  4. The better the box, the better prepared the metal was before painting. This affects durability, but it also affects the comfort and safety of the user, as Chinese Slave Labor Factory Nº 76214 tends not to de-burr metal, and instead leaves sharp edges on everything.
  5. The better the box, the more likely you get extras like drawer liners.

However, if your budget only extends to cheap Chinese, there’s a few things you can do to get closer to the $4000-box experience. For example, being aggressive with abrasives and touch-up paper can keep rust from gaining a toehold on your toolbox. (So can dehumidifying the working environment). Likewise, patience, red ScotchBrite, and touch-up paint can correct for lack of deburring at the factory. Don’y hesitate to get a rubbery (and contrasting) drawer liner material; this will keep the bare insides of your el cheapo box from getting all beat up, and save your tools some scars along the way. And you can hunt for used or estate sale boxes. One day ours will be for sale this way!

Our intent is to have the Ghost Gunner related tools in the top drawer and the tooling (jigs/fixtures and fasteners) in the second drawer. Since we’re currently just using the factory AR-15 jigs, and the top drawer is full of cables and pulleys for another project, everything’s in the second drawer.


Clockwise from 12 o’clock, the tools are:

  • 12-3:00: The white tray is a separator we had handy, not our ideal one, and its contents are extra M4 fasteners. We keep duplicates of all the standard jig fasteners: M4-20, M4-45, and appropriate nuts and washers (it was pretty inexpensive to buy all of these). We also have some M4-50s that are used with a bunch of washers to create an M4-51 equivalent when the M4-45 doesn’t quite reach. The Fastenal bolts are made in Taiwan and the washers and nuts in China, and they come with lot numbers for tracking, which is not required for our purposes.
  • 3-4:00: We have some manuals tucked in here. And an extra box of M4-20s just for GPs.
  • 5:00: A Sharpie, a small magnetic wand, and a nut driver set up for the M4 nuts (that’s a 7mm socket).
  • 6:00: The bolts for the two standard setups on the AR-15 milling process.
  • 7:00: More jig bolts. One of these is the above-mentioned M4-50 with extra washers, and one has a small printed nubbin that shows that it is the bolt that goes through the pivot pin holes.
  • 8:00: Appropriate Allen keys (3mm) for the M4 bolts, drill bit and end mill, ER-11 collets.
  • 9-11:00: Mallet and assorted open end wrenches. The shop’s lousy with mallets and wrenches, so we probably didn’t need to put these in here, but it’s a timesaver to have extras in here, and it’s not like they’re our only ones.
  • 12:00 and Down to the Center: The three-component plastic jig for working on the AR lower receiver to the right of the simple rubber-headed mallet mentioned above. As they’re black on a black drawer liner they might be hard to see.

Stay tuned for further reporting on this remarkable tool. Happy building!

Note: the GhostGunner is a simple, compact CNC mill developed as an open-source project by Defense Distributed. The long-term plan is for it to be at the center of an ecosystem of technology, information, and shared files. That is currently suspended due to a legal attack by anti-gun appointees in the State Department.

A Rockin’ Mystery

Here’s a video Ian did over a year ago, about a gun that was up for auction at Rock Island Auctions. It beats us with a stick, but it also beat him with a stick, which takes a little more doing. And it beat his commenters with a stick. In the end, it didn’t sell at the auction.

He said this in the text area to the video:

There isn’t much I can say about this one, as I have no idea who made it or when. What I can tell is that it is a blowback action with a rather unique “rocking block” type of bolt and what appears to be a clock style coiled flat spring for the hammer.

And elaborates on that in the video. He does do a credible job of explaining its unique method of operation. He doesn’t comment at all on markings but it looks to us like it might have some kind of proofs up above the barrel. What do you think?

Rock Island also had limited information about it, and no provenance that might help out.

Description With no markings and a unique angled slide. The pistol appears to be almost entirely handmade with a smooth unrifled barrel, hand checkered grips, hand checkered cocking piece and a hand checkered trigger. The rounded spur hammer seems to work on a simple leaf spring mechanism and is vibrantly colored from what appears to be a rudimentary heat treating process. A very interesting piece with a “rolling block” style mechanism.
Condition Very good with traces of blue finish. The balance has a mottled gray/brown patina with some light spotting and minor pitting. Grips are fair. Mechanically needs adjustment. The leaf spring for the hammer appears broken or detached.

As we said, it failed to make reserve at the auction and so was a no-sale and returned to consignor.

And as far as we know (again), nobody’s ever figured out what it was, found a related patent, or anything.

Wednesday Weapons Website of the Week: Serbu Videos

Today we’re not calling out a website so much as one guy’s, and one company’s, YouTube channel. Mark Serbu’s Serbu Firearms is known for its .50 rifles and other innovative products, which manage to combine shade-tree mechanics with practical engineering. But his YouTube channel is something else entirely.

For instance, he unearthed this video of a mid-2000s prototype .50 BMG semi-auto, the HyperDel, which seems to have vanished, since. It was a 5-round semi .50 with a tubular receiver and a Stoner-style direct-injection gas system. The barrel is screwed into the receiver with a racheting barrel nut à la Uzi. It looks like the trigger and hammer are AR-sourced, and the mag release resembles the M-14, Tokarev, AK style. It seems to have a cross-bolt safety on the receiver, but we might just be seeing that wrong.

The recoil-management and -measurement rig is pretty clever and straightforward. It looks like they went back to the drawing board after this video. Not only does the video have some possible gaps, the “design enhancements” suggest that the prototype had failures to fire, feed, and extract. According to Mark, this company did not advertise completed guns, only plans.

This thread on the Home Gunsmith forum suggests that Hyperdel (Hyper Delivery Systems) was selling the plans before they ever built the rifle, which seems a bit ass-backwards to us. A look at yielded these claims from 2006:

The Patented hyperDEL semiautomatic big bore rifle, chambered in either 50 BMG or 50 DTC Euro calibers, is now undergoing the second of four, live-fire, test phases. See News for more information.

Caliber: 50 BMG or 50 DTC Euro
Dual Caliber Rifle, Barrel Assy Interchangeability

Patented hyperDEL Gas Reciprocating Action
ON/OFF Gas Toggle for Bolt-Action-Like Touch-Offs
hyperBUFFER Adjustable Damping System
Free Floating 29 in. Kreiger Barrel, Chromed Chmbr
Dry Weight: 30 lb. (no scope, no ammo)
Overall Length: 60.1 in.
Four Lug Bolt and Barrel Extension
Alloy Steel Barrel/Action Construction
Aircraft Aluminum Receiver
Patented hyperTAME Recoil Brake
Patent Pending hyperTIGHT Group Size Reducer
Fixed Head Space
“AR15” Fire Control

Pistol Grip for Man-Sized Hands
hyperLIGHT Trigger Break
Patent Pending hyperPOD Bipod
Two 10 rnd., Dual-Stack, Parkerized Steel Mags
Ambidextrous Magazine Release
Magazine Accommodates Both Calibers

Finishes: Hardcoat, Parkerizing, DuraCoat®
Easily Breaks Down into Receiver & Barrel Assys

Field Strips w/o Tools
Rotatable Butt Pad To Fit Any Shoulder Pocket
Sorbothane II Shock Dissipating Butt Pad
MIL-STD-1913 Picatinny Rail, 50 MOA Declination
Closed-OFF Ejection Port While Bolt in Battery

By 2010, the site was occupied by domain squatters, cheating advertising networks with bogus searches and hits. It last resolved in DNS at all in 2015.

Recently, Mark has been engaging with the much reviled experimenting kid, Rick, whose YouTube persona is Royal Nonesuch… helping both to educate the boy and keep him from killing himself. We suspect that Mark sees in the tinkering youth a shade of his own young self, and his own tinkering keeps him young at heart.

Of greatest interest to readers, perhaps, is his series Gun Design 101 in which Mark originally intended to talk about conceptual and detail design (like some of the books on our Gun Design Books page linked at the top of but has wound up, instead, talking design of simple, almost improvised, firearms. So watch these three videos, and be Ready for Hillary.

December 2014: “The Making of the $7 12-Gauge Zip Gun Shotgun”

He calls it the ZG-12 for “Zip Gun 12,” heh, and doesn’t give dimensions directly as a “barrier to entry” — if you can’t figure it out, he says, you’re a “punk.” It’s not a terribly practical gun, but it exists “as a testament to what can be done,” with minimum costs, materials, and time.

The video is actually a good “Design 101” because it shows the conceptual design and engineering substantiation of the firearm, as well as its production. If you’ve been listening to Dyspeptic Gunsmith about the power of a file, you’ll be nodding along when Mark applies the unexpected combination of a massive industrial CNC turning center and a hand-held file together on the same operation!

Firing the gun lets him check his calculations.

Even in oppressive environments where guns are outlawed, the last ammunition to become unavailable is birdshot.

The next video in Gun Design 101 makes a slam-fire .22 pistol.

May 2016: Apocalypse Hardware Store Gun Build!

“We’re not talking a complete apocalypse, where you’re running around in a loincloth in the woods.” And “We used some pretty expensive equipment, but we didn’t have to.”

And the latest (and possibly ultimate?) version: the GB-22. The “22” in the name is obvious… the “GB” stands for “Gun Buyback,” which is one suitable deployment for such a firearm… used to convert doo-gooders’ cash into money to buy that Serbu .50 you’ve had your eye on.

October 2016: World’s simplest homemade pistol…the GB-22! Gun Buybacks beware!

“16 years ago I came up with the idea for this really simple gun to turn in on a buyback.”

World’s simplest homemade pistol…the GB-22! Gun Buybacks beware!Skills displayed here include making and heat treating a spring with improvised tools, including a toaster oven as a heat-treating oven (including a temperature botch that didn’t produce the desired temper)


Ghost Gunner Tips and Tricks #1

We have found a few tips to pass on to you. Mostly by a griefsome cycle of trial and error:

  1. As far as we can tell, the Windows and Mac apps work identically, with the exception noted immediately below in #2.ddcut00 As die-hard FOSS fans, they’d like to have a *n*x version and open-source it, but as you’ve probably noted, they’re up to their alligators in lawsuits, and the State Department’s gun control squad is trying to ban the dissemination of technical information. But right now, you can name your poison, so long as it’s Apple or Microsoft.
  2. We have had an inexplicable hang with the Mac version. It just reached one line of code and sat there stupidly spinning the spindle, not connected to anything. We waited ten minutes, it kept on spinning. We took the dog for a half hour walk, which wound up being a 20 minute walk because he wanted to run the leg back, and stooged around on Gun Broker not buying stuff for a few minutes, and the thing had been spinning for 45 minutes at least. We wound up having to nuke both the GG and the Mac (hard reset).

    Most of the time, it just made chips, happily.

    Most of the time, it just made chips, happily.

  3. Keep the work area clear at all times. In addition to the Lord-knows-why system hang described above, at one point, a book fell upon our keyboard, causing DDcut to hang in mid-operation. We waited for ten minutes while it sat there, spindle spinning. Then, we found that the Emergency Stop button did not work. (Pulling the USB cable produced an emergency stop).. In this case, we didn’t have to reset the Mac.
  4. If it does shut down, the workpiece can usually be saved, at some cost in time. One hopes you will never need the rest of Instruction #4, but just in case, here’s what you have to do:
    1. Depower the unit. There’s no switch; just pull the plug.
    2. Remove the workpiece. (This is a good chance to deal with the collected aluminum chips. A tiny cube of 7075 forging becomes a spectacular volume of chips). You may have to ease the workpiece carefully off the tool.
    3. Loosen the collet cap and remove the tool. You have to do this or you will crash the tool into the base when the machine goes to find zero early in the .dd, before the tool is supposed to be installed. You do not have to remove the collet, because you’ll be returning to the same tool that the system hung on last time. (Two collets are provided because the drill and end mill have different shaft diameters).
    4. Restart the whole operation on DDCut from the beginning. Let DDCut walk you through the reinstallation of the part and tool. Don’t worry about the workpiece going back to the exact same place — the mill will automagically touch off again to locate it. Although you have to start from the beginning, and although DDCut will process every line of code again, it will not take as long to get to where things went sideways last time, because on the parts that are already cut, nothing will slow down the tool. On each cut, DDCut waits for the machine to tell it it has completed the movement before it sends the next line of code (you can see these OKs pass in the code window).
  5. Before you get to any possible shut down, of course, you have to run DDCut for the first time. At first, it’s not very obvious what to do when the application window opens. You have to have the GG plugged in to power and to your computer via USB. It will announce itself cryptically, based on the Arduino board inside it. ddcut01It’s probably a good idea to have a minimum amount of weird stuff plugged into your computer at this point.
  6. Next, you have to pick a file. When you’ve selected the GG and the file, the screen looks like the image above, and you can click, “next.” The files include a GG2 version of the AR lower, an original GG version, and a version that drills the holes. Two setups are needed: one for the milling, and one for the holes.
  7. As far as we can tell, it doesn’t matter whether you mill first or drill first, as each operation’s file and process is self-contained. However, you must follow the process through to the end and remove the last process’s tool and collet.
  8. While the provided open-end wrenches work, tool changing would be faster if we had a ratcheting box wrench that fits the 17mm collet cap. Our set of ratcheting box wrenches skips from 15mm to 18mm, but maybe you have the right one.
  9. A narrow- or small-diameter magnetic wand is a great thing to have when (not if) you drop a small fastener inside the rig. Since the bottom is open, it’s always easy to get the dropped washer or screw out, but it’s easier if you have magnetism on your side. Same goes for tools and collets.
  10. The furnished molded plastic jig really doesn’t want to go on a mil spec-forged lower. A healthy thwack with a rubber mallet resolves this.ghost03
  11. Note the takedown pin well has been pre-milled on that lower above. That’s the only kind of lower that works. Nothing like the lowers shown below will work with the factory jig and setup (raw forging, early-AR retro w/o takedown pin well, HK416 w/o well). The documentation warns of this.ghost05
  12. It was difficult to tie down the jig with the provided M4-45 bolts in all positions, especially after we buggered the very tip of one of the threads.We wound up running out to Fastenal for extra M4-45s and some M4-50s, and a whacking great bag of M4 washers. (If you look closely at the top photo with chips flying, you might be able to see that the lower left tie-down bolt is an M4-50 with a 4mm stack of washers!) Also, a generic  AR-15/M16 grip screw is required, but not provided. Most AR builders have them kicking around, but if you don’t, the part you want at Fastenal is: 1/4-28×1″. These are available with various heads. Original Stoner design used a flathead screw. We recommend a socket head cap screw, just because a socket head is always easier to remove and replace (and less likely to screw up) than a flathead. The factory AR screw needs a really big flathead blade, the very biggest blade in a Wheeler gunsmithing kit fits. The benefit of the flathead is that it’s always easier to find any size flathead screwdriver than a hex driver, and you can, albeit at the expense of the screw, use a somewhat undersized flathead driver in it, if you haven’t got the right one.
  13. Lining up the t-slot nuts can be a challenge. Another small wand, this one with a mirror, helped, but we also found the a long 3mm Allen key worked OK as an alignment pin.
  14. You’ll want more tie-down hardware, even before you start designing your own operations and jigs.
  15. Never skip a step in setup. Be sure! Some steps, you can back out of with a Previous button, and some steps you can’t.
  16. Take the directions as literally as an Aspie. When they say tighten something as much as you can, do that. When they say don’t over-tighten, do that. When they say put the screw in finger-tight, don’t decide that you can go ahead and tighten it the rest of the way — at one time, they tell you to finger right the jig screws down, and after that is done, clicking “next” tells you to slide the whole jig-and-lower assembly in the tracks, which you can’t do if it’s tightened down. Like most of these tips, don’t ask how we learned this.
  17. It wants you to adjust the jig and lower, on installation, so that the end mill (which is inside the mag well) is 1-3mm from contact with the after surface of the maxwell. This is a good time to remember that the Allen key you used to tighten the M4-45 (or -50, with extra washers) bolts is 3mm across the flats. It makes a serviceable feeler gage. (Precision doesn’t count that much here. The mill will touch off against the receiver automagically to locate the part in all three axes).
  18. It’s pretty loud when roughing (60-80 dB by uncalibrated measurement). Not hearing-threatening, and you can converse over it without shouting, but not pleasant. So you might want to think about where you put it, and step out while it’s graunching away. If you’ve got to have it in an office or a quiet shop, you’ll need a silencing enclosure as are sometimes used for server farms.
  19. It keeps its chips pretty contained and is easily tidied up. A Dustbuster lets you collect all the little shavings (fireworks, thermite, anyone?)ghost07
  20. If you multitask while you work, don’t come back into the application and click the Emergency Stop button. On the other hand, the Emergency Stop button works when the system’s not hanging.
  21. If you Emergency Stop, or head crash, the tool might be left in a place where it can’t be removed by the two-wrenches technique that you used to install it, because the collet is behind the face plate. Don’t despair. Unplug the unit for safety, flip it on its left side, and go in through the bottom.
  22. In case you haven’t figured it out yet, have a few extra 80% lowers, any time you’re experimenting with the unit. Don’t decide to learn it on the one you already had engraved….

ghost01And finally, don’t take the above the wrong way: the thing is a blast to use and learn.

Tracking Point: Precision has a Lower Price

We’ve been big boosters of Tracking Point throughout all its business and technical drama, and why not? The company leverages technology to make a rifleman (or -woman, or gelding, even) more effective at that first, cold-bore shot, night or day.

That’s a big thing.

There’s a big real-world gap between potential and performance, and it’s very apparent on that cold-bore shot.

The thing that’s limited (to put it mildly) take-up of the technology has been the sting of early-adopter prices: $20-30k for a Tracking Point Precision Guided Firearm.


Now the company has an offer that brings Tracking Point ballistic potential closer to the average AR-toting schlub’s financial potential. For a limited time, their M300FE 5.56 mm Precision Guided Firearm is for sale with the most popular options, night vision, included for under $6k.


We didn’t get around to blogging this the first time they sent it to us this week, so they enlisted a new spokesman: St. Nicholas.



They point out:

Santa is a conservative. He wears red and never wishes anyone “Happy Holidays!” He’s bringing you Christmas early because he is concerned about what will happen after November 8th. It’s time to get ready – for Christmas and whatever else might be coming our way.


The lower price is temporary, officially, and the best deal is only available to the first hundred buyers. That includes a grab bag of extras and further deals:


First 100 Orders 

  • FREE Gen-2 Night Vision $2495 value!
  • Immediate Delivery –  Order Today, Ships Today!
  • $200 off ShotGlassTM!
  • Special Financing 90 days same as cash!*
    *Extended Financing available with payments as low as $137 per month

As they put it in their email, “Don’t becwait for the tree to go up! Santa will be backlogged.”

The capabilities of the M300FE are a combination of the full-house Tracking Point technology and some simplification to reduce costs. For example, special low-trajectory high-velocity ammunition is required (which is sold by Tracking Point, naturally). Because of the ammo’s point-blank to 300 m capability, they can dispense with integrating a laser ranger into the 22 calculations used in setting up every shot.

Some of the capabilities are software-limited, like target speed and lock range. You can track a target at a target velocity of up to 10 MPH — sufficient for foot-borne humans, certainly, but likely to fall short when taking shots on running hogs.

Utilizing TrackingPoint’s new high-velocity UltraFlatTM ammunition the M300-FE shoots point-blank range out to 300 yards so there is no need for an internal laser range finder.

The operation of the system sounds like it’s a little simplified from the earlier tag, track, exact system:


As a shooter pulls the trigger the target is acquired, tracked, and measured for velocity.  By the time the shooter completes his squeeze the target is inescapably captured and instantly eliminated.

It does, however, include the four modes of all current TP firearms: Suppressive Fire, Precision Fire, Auto-Acquire and Night.

Suppressive Fire mode video:

Precision Fire video:

Auto-Acquire Mode (useful for multiple shots on single targets):

Night Mode with Gen2 NV (as included with the first 100 M300FEs, free of charge):


This mode does not seem to be included in the M300FE: Precision Movers.

The ShotGlass system is an unusual extension of the rifle’s capability. Essentially, there’s no need to be behind the rifle to shoot it (although you do have to have access to the controls, especially the trigger). There’s no need for the shooter to expose himself, just the rifle. He sees in the ShotGlass glasses exactly what he’d see looking through the rifle’s digital “scope.” It’s an extra-cost option (

For more information:

And no, this doesn’t make snipers obsolete. Actually, technology like this should increase the advantage of the trained sniper, both in his shooting and scouting

GemTech GSBC Suppressor Bolt Carrier under Evaluation

Interesting goings on going on, and one of them is constant tinkering with the Mk 18 carbine in the SOF world. One of the things people are doing is running them suppressed sometimes, and not suppressed other times. The word is that this bolt carrier helps make that change in a regular, direct impingement AR like the Mk 18.


The Mk 18 (or the CQBR upper for the M4A1, which produces the same functional weapon) is widely issued within SOCOM and somewhat beyond it. For example, Marines who need such a carbine have them, but Uncle Sam’s Military Club runs them with some different accessories than the SOPMOD gear commonly used in the other branches’ SOF.

Running suppressed is more and more widespread (in conventional forces as well as in SOF). But there are several downsides to a suppressed DI AR. Taken together, these add up to one of the key impetuses to the development of the piston HK 416. But experience has shown arms developers that it’s possible to make a DI AR run well, while suppressed; what has been a challenge is to make the same AR run equally well with the QD suppressor on or off.

To recap the problems:

  1. More pressure than designed into the gas system, yields…
  2. More blowback out of the ejection port, plus…
  3. Much higher carrier velocities, producing
  4. Higher perceived recoil
  5. Higher cyclic rate on AUTO
  6. Reduced reliability, and
  7. Reduced durability.

Gemtech’s solution is so simple that the instructions for using it are pretty much contained in these two box cover illustrations:


The valve flange is on the left side of the bolt carrier. To change it, then, you must remove the BC from the firearm. You can then turn the valve flange to (S) for Suppressed or (U) for, you guessed it, Unsuppressed.

When you’ve made such a change, or, for that matter, at anytime the GemTech Suppressed Bolt Carrier is installed, an indicator visible through the ejection port shows whether you’re configured to run Suppressed (S) or Unsuppressed (U). gemtech03That’s pretty much it. The setting indicator arrow points aft to S, or forward away from S, and makes the whole system fairly Ranger-proof.

The GemTech bolt carrier is adjusted with a flathead screwdriver, but other tools will work in a pinch. The valve can get a little gummy.

gemtech02The GSBC comes with the carrier key screwed and staked in place, but otherwise it is a bare carrier. It is conventionally notched for use with a forward assist. It lists for $249 and can be bought direct from Gemtech or from Gemtech dealers.


Here’s a close-up of the flange where the valve can be adjusted. gemtech06

Gemtech’s claims of reduced carrier velocity and reduced cyclic rate are supported by an analysis by Philip Dater, available on the Gemtech website (.pdf). The reduction was significant on several different weapons, but much larger (25%) on an M4A1 than on a Mk 18 (16%). Still, that’s not trivial.

Clandestine Gunmaking in the Phillipines

In 1997, the Filipino government decided to take a novel approach to stamping out the underground armories in Danao City, Cebu Province: they would bring the underground gunsmiths in from the cold, by establishing new gun factories in Danao. They licensed two manufacturers — who had no problem finding skilled workers.

That was then, this is now: the guerrilla gunsmiths of Danao still flourish, underground; they work in remote jungle workshops to stay off the authorities’ radar, so as not to have to pay stiff bail (or bribes) to get or stay out of prison.

AR-15 Lower: How a Midsize Manufacturer Does It

Most manufacturers guard their manufacturing processes about the way KFC guards Colonel Sanders’s 11 Herbs and Spices Coca-Cola guards the Coke recipe. They would no more show you a video of lower receiver machining than they would give you the product. Indeed, some mnufacturers not only won’t let us tour their plants, they won’t give us still photos, talk about processes, or even let their own workers bring smartphones or cameras in certain areas.

A time- and money-saving way to do a standard process can be that big of a competitive advantage.

But here’s midsize manufacturer Palmetto State Defense using a 5-axis machine to take AR-15 lower receiver forgings to 80%.

To us, it was interesting to watch how they rough milled the magazine well to approximate shape, and then CNC broached it to final shape (the rasp of the broach is unmistakeable). The end mill removes lots of metal fast, but the broach gets net shape and surface finish up to standard.

Note how much coolant/cutting fluid is used on these operations!

The link at the YouTube page no longer takes you to a buy page; PSD no longer sells the 80% lowers, apparently. They do make some attractive finished rifles, and one thing they’re selling is 200 rifles that were, supposedly, used in the Range 15 movie. (At press time, they still have 92 5.56 and 95 .300 Blackout rifles in stock). See ’em here.