Fishbreath Prints: the Glockblaster 3D

First, there was the Glockblaster. It’s parvusimperator’s favored carry Glock 19, with its micro red dot and its little compensator. Then came the Glockblaster 2 and Glockblaster 2.0, two USPSA project proposals parvusimperator and I both considered, then ultimately dropped1.

Now, there’s the Glockblaster 3D2.

The Glockblaster 3D is a project I’ve been wanting to tackle for some time now, and recent and upcoming stimulus checks provide the perfect excuse. I mean, the perfect reason. In short, the goal isn’t to build an everyday USPSA Open gun. The goal is to build a to build a .40 S&W3 Open gun using about as many 3D-printed parts as I can get away with4.

The obvious place to start, since the ground is well covered, is the frame. There are a number of options out there, but the best one was just released: the Defense Distributed G17.2, recently released by one Ivan the Troll, noted 3D printer gunsmith. It uses milled metal rail sections secured by pins front and rear, which helps out in a later step.

I may have gotten a bit ahead of myself, though—why a Glock in the first place, among all the printable options? Even if I’m not a Glock guy, the arguments in its favor I made in my Glockblaster 2.0 post still hold: the aftermarket isn’t there for any other option. The Glock is the de facto AR platform of the pistol world, even if the P320 has a better claim to the title given its design. Triggers, internal parts, and partial and complete uppers are all dead easy to find. Expertise is a bit harder to come by, but our very own parvusimperator happens to be a bit of a Glockhead, and is interested in seeing how this project goes5.

So, Glock it is. What do I want to get out of the project? As I alluded to earlier, what I don’t need it to be is a daily-driver competition gun6. I’m happy in Revolver, and plan to shoot it to the near-exclusion of all other divisions for some time to come. So, the Glockblaster 3D doesn’t have to be especially reliable, or especially good at its job. It’s a 3D printing technology demonstrator on the one hand, and a silly range toy I can take to matches for the afternoon shoot on the other, and if it jams up or disassembles itself, so be it.

Unlike a lot of my projects, this one isn’t as simple as buying a bunch of parts and putting them together. I see seven steps between where I am now and a completed Glockblaster 3D.

Step 1: finish a frame in PLA

PLA is easy to print with, and durable enough to make a frame that’ll stand up to both 9mm and, eventually, .40.

So, to get my feet beneath me in the field of making Glocks from nothing, I’m going to to start here. I’ll print a frame in PLA, buy the rails and parts kits I need, and get to a working frame.

Step 2: finish functional 9mm build

Parvusimperator has a Glock 17 upper I can slap on to see if everything fits, and perhaps even if everything works live.

I don’t know if I want a 9mm upper myself, at least at first. It depends in part on what kind of money the US government decides to send me. Given the parameters of the project (‘build a .40 Open Glock with 3D-printed parts’), spending money on a 9mm upper seems like a distraction. On the other hand, if I build a 9mm upper using a .40->9mm conversion barrel, I’m only out the cost of a barrel, and then I have something to shoot between this step and the end of the project. Plus, I can modify the rail units as required for a .40 slide without having to worry about 9mm function later.

So, I guess we’ll see.

Step 3: set up the printer for nylon

For something with long-term durability, I’m going to want a better material. In the past, PLA’s strength has surprised me, and its mechanical properties are sufficient for printing firearms, but nylon has two advantages.

First: it’s slipperier than PLA, which is good for parts that interface with metal. A slide whipping back and forth on top of nylon will do less damage to the nylon over time than it will to PLA. Second, and more importantly: nylon has much better performance at high temperatures than PLA, and will easily stand up to a match on a hot day, or being left in a hot car.

To print in nylon, I’ll need a hotend for the 3D printer that can push filament at about 270C, or 30-40C hotter than is wise to push the current hotend can7. I may also need an enclosure for the printer, which keeps the print area hotter to limit warming, and will definitely need some filament drying supplies: a box with some spools in and a layer of silica gel on the bottom, to keep dry filament dry, and a food dehydrator to turn wet filament into dry filament. (And also, perhaps, to make beef into match jerky, although I’ll have to look into whether it’s safe to use the same food dehydrator for both items.) I think I’d probably want to invest in an air purifier for the printer room, too, not for nylon specifically but just because it’s good for our indoor air quality to suck up all those VOCs and microparticles.

All of that makes for a fairly expensive and fairly involved process, so that brings me to step 4, which I can work on at the same time.

Step 4: make a sight mount for the DD/FMDA Glock

SJC makes perfectly serviceable Glock sight mounts that don’t occupy the accessory rail and don’t block the ejection port, but they require drilling into the frame to make a second pin hole. The FMDA Glock, on the other hand, has a pin forward of the trigger guard, for the front rail unit, that can be used as a second anchor point (along with one of the locking block pins).

That front pin is featureless and thus easy to replace with a longer one. Both pins above the trigger guard, however, have additional features: the locking block pin is slightly dumbbell-shaped, with wider ends and a narrower middle, while the trigger pin has cuts into which the slide release fits to help retain it.

I am not a Glock guy, so I don’t know if those cuts are function-critical. My hope is that the locking block pin can be replaced with a featureless, non-dumbbelled one, which makes the task of designing a sight mount super-easy. (Although I may still have to have it printed by some manner of print house, so I can have it glass- or carbon-fiber-reinforced for stiffness.)

If the locking block pin can’t be so replaced, then it’s on to hooking into the trigger pin. I’m pretty sure, based on how the SJC sight mount is attached, that the cuts on the trigger pin are purely for anti-walk, and for a technology demonstrator like this, I can either omit them entirely and just push the pin back into place when it starts moving, or cut them in myself with a dremel.

Step 5: build a .40 upper

Now we’re getting into the home stretch.

A .40 upper requires a slight tweak to the lower: I’ll have to modify the front rail unit to allow the slide to fully cycle. Happily, it’s not a hard modification—just need to shave a bit off of the front so that the slide doesn’t crash into the rails, and a light chamfer with a file or a dremel is not hard to achieve.

I haven’t decided yet if I want to do the Glock 22-length slide or the Glock 35-length slide. On the one hand, the latter adds weight (good!) and gives me a bit more room to hang a weight under the front of the gun without getting in the way of the eventual DAA holster block (also good!; saves me money on a different holster).

On the other, the Glock 22-length is actually tested, and parts availability is a bit better.

I think I probably lean slightly toward the 35-length, because I like giant handguns.

Step 6: compensator, spring tuning, etc.

SJC sells the benchmark Glock compensator, an 11-port number that seems to work fairly well even in its .40 version8. Not much more to say about it. This is one part I clearly can’t 3D print, not that it isn’t tempting to try with a prototype and a laser-sintered version.

Spring tuning includes both recoil spring (to get the gun to run well with the compensator) and trigger work. Since I shoot Revolver in USPSA by day, I think I want a Walther-style ‘rolling break’, emulating the wheelgun’s double action pull. That’s easier to achieve than glass-rod break on partially-cocked striker-fired guns anyway.

Step 7: random Open accoutrements

USPSA Open lets you do just about anything you want. I have a few ideas that go from normal to silly.

Normal idea 1: a slide racker in place of the rear sight. Because the sight mount covers some of the slide, there aren’t as many ways to get your hands on it. A slide racker gives you a knob or handle of some kind to grab, resolving the problem altogether.

Normal idea 2: frame weight and brass magazine well. A magwell is a traditional Open gun feature. Making it out of brass adds a bunch of weight, which is good on lightweight guns like Glocks. SJC makes one, although I’ll have to modify the frame to attach it.

The frame weight is also a traditional Glock item, adding weight to the gun and also reducing muzzle flip. In this case, I think I’ll have to roll my own: the existing options don’t play nice with the DAA holster I have for the revolver, and I don’t feel like buying a new holster for this goof-off gun.

Silly idea 1: a Radetec RISC bullet counter. I’m pretty sure that it doesn’t do any detection of reloads, and since I wouldn’t expect to be shooting to slide lock very often, it’ll be wrong after I drop the first magazine. That said, given the constraints of USPSA, I don’t really care. It’s 75% about looking cool anyway.

Silly idea 2: a tuned mass damper in place of a frame weight. A moving mass on a spring, damped by either liquid or a near-airtight fit, seems like it might help? It worked for the Renault F1 team in the early 2000s, anyway, and a gun moving back and forth shooting doubles is kind of like a stiff suspension moving under load.

This, I think, is the most silly of my ideas, but it’s an indication of a greater truth: 3D printing makes prototyping a silly tuned mass damper for a pistol a matter of a few hours of CAD work and a few dollars of filament. I can explore random things like this with effectively zero cost.

Conclusion

Well, that’s my plan. I’m not expecting to get it done anytime especially soon. I’m about midway through Step 1 now, and there are a number of demands on my finances I consider more important than this.

As I make progress, I’ll be sure to keep you up to date.


  1. He decided to get a real Open gun rather than putz about with trying to turn a Glock into one. I was fine with the putzing around, but decided I’d rather shoot Revolver, so neither Glockblaster 2 nor 2.0 ever existed beyond our imaginations. 
  2. It’s supposed to sound like a bad 80s movie, in the vein of parvusimperator’s Glockblaster 2: Glockblast Harder post. 
  3. I think I’ve gone into ‘why .40’ in the past, so I won’t relitigate that issue here, beyond to remark that it’s still because the project parameters don’t require me to have 30-round magazines. 
  4. I say ‘about’ to leave myself wiggle room if I decide that prudence should dictate I buy a part instead of making it. 
  5. Possibly interested in the same way as people who watch videos of Nurburgring crashes or that one can-opener bridge, but I haven’t asked and don’t intend to. 
  6. If it turns out that it’s that reliable, I won’t complain. Ignore the sound in your head; that’s parvusimperator’s muffled laughter. 
  7. The standard Ender 3 hotend has a PTFE tube that runs all the way down to the nozzle. This is good, because PTFE is low-friction; this is bad, because PTFE offgasses neurotoxins at temperatures above about 250C, and I don’t want to sniff (if you will) that temperature. 
  8. Received wisdom in USPSA is that compensators work best with light bullets going fast, because a light bullet going fast enough to make power factor requires more pressure, which means more gas coming out the end of the barrel, which means more power to the compensator. 

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