The double barreled shotgun is a weapon I find particularly menacing. It's got the ability to pepper the target with pellets, and if it's sawn off then you're also probably going to be hitting the surrounding area as well - so it's a real room-cleaner. The general design and simplicity of reloading also makes the gun more thuggish - because an intricate, complicated mechanism would make this "interesting" ...instead of just giving it an essence of brute force.
I've taken a bit of a step away from my usual "model replica" here - because it started out as a VG Bentley replica (think Mad Max), but I found the grip far too long to hold comfortably so changed the shape a fair bit. The lucky thing about double-barrels is that they're relatively generic, compared to the things I normally make, so this tweak didn't make the gun lose any authenticity as a "double barreled shotgun", even if it wan't quite what it set out to be.
So... there's not really a "feature list" to create here, because, as we know, double barrels are inherently very simple. Essentially, mine has a two-trigger setup (front trigger fires right barrel), a simple break-open catch, and fires bricks (with power to rival the Jungle Carbine, in fact!). There are two hammers, both cocked by the same hidden cocking handle (hidden inside the foregrip), and an interesting design point is that the hammers travel past the hinge. That is to say, they start in the front part of the gun, about half-way down the barrels, and then when cocked, they lock into the rear part, just under the break-switch.
One of my favourite parts about the hammers themselves is how they work. I was faced with several possible ideas of how to cock them (including a lever that cocked them when the gun was broken open), but the one I went with involved cocking the hammers separately. In order to not leave the bands stretched for too long etc, I thought it would be better to allow the hammers to be cocked with or without any bricks in the chambers. This presents a problem though. In previous builds, the bricks would be in magazines, and when the hammer past over them, they would simply be pushed lower down into the magazine. You can't do this with a chamber though, because the brick is essentially locked in place. My eventual solution was to create a hammer with moving parts, and it turned out to work very nicely. Essentially, the hammer features some fixed wider parts that slide in the rails to guide it down the barrel, and a sort of "ratchet pawl" part, that is sprung by one of the hammer's rubber bands and allows the whole thing to collapse slightly as it passes underneath the brick in the chamber. Problem solved!
There are more things to mention, but I've already rambled for long enough here, so I'm going to start the picture run. Build diary a few pictures in!
Another view - notice the red "cartridges" in the chambers
The Break Catch - this actually got re-designed while taking the photos for this post, there's an updated version lower down.
Broken open, showing empty chambers
Underside - notice the hidden cocking handle (it goes to the very front of the grip)
Two fingers on the triggers (this may be very bad practice, I've never been taught how to use a double trigger setup!)
Down the "sights"... this would normally consist of just looking straight down the barrels, but here we see a lump sticking out at the near end of the barrel: this is for locking the bricks in place when they're in the chambers
About to cock it
The two halves separate by simply removing one 7M axle. The two 0.5M thick 4M long liftarms sticking out of the back half are used to disable the cocking handle when the gun is broken. This stops anyone cocking the gun open, and finding the hammers have fallen off because they've run out of rail to slide down!
Looking down the barrel, you can just make out the hammers towards the main inside wall
Looking in towards the trigger mechanism of the back half
The (old) Break Catch (built with a sneaky bit of SNOT). When this is attached, the catch itself slides on top of the top-most technic beam shown in the next picture.
View of the top of the back half, with the Catch removed. As the hammers were only 1.5M wide (and this involved some piece modifying, I add), the best way to create rails for them to slide down was to use technic bricks with flats on as the "walls" (if sideways), and normal liftarms for the "trough" parts
The entire back half, "field stripped". The back half wasn't a very modular build, as shown by all the little bits that had to be removed before I could prise off the main wall.
Closeup of the trigger mechanism(s). Notice the filed down "1M" pins, the same ones that were used in the Desert Eagle. Again, they were incredibly useful due to having to fit everything inside a 4M wide body.
Front half. This is a closeup of the method used to "join" the top beams to the bottom ones - a clotheshanger piece and a 5M liftarm. Other ideas are shown in the build diary!
Underside of the front half, with the bottom plate removed. The "fingers" that mesh into the back half to form the hinge have been exposed
The front half turned out to be much more modular than the back. Here I've removed one of the lower walls, exposing the right hammer and the "bolt" part of the cocking handle. This was the third version I made, the other two had various faults that kept making them break.
Front half entirely stripped
This seemingly innocent combination of parts felt like a stroke of genius - it creates a sort of lock, to fix the two walls together.
The pins fit into corresponding holes in the two walls, and the brown axle is then pushed up into the barrel-module to lock the pin itself in place.
Having the extra 4M liftarms on one wall helps when arranging the rubber bands from the hammers and the cocking handle around the various parts of the inside
The hammers and the bolt/cocking handle, all removed. Note how the hammers are spring-loaded to expand, and how this is only powered by one of the three bands. The grey axles here were originally two 3M axles, but got cut in half to form four 1.5M axles.
Detail of how the hammers get locked in their rails by the trigger mechanism. Ignore the placement of the hammer's bands, that was only done to keep it in place so I could take the photo.
The entire gun, stripped into all the little bits
The updated Break Catch. The catch itself isn't that much different, but...
I've replaced the 5M liftarms with 4M tiles, because the hammers were occasionally springing themselves too far up and getting stuck in the holes (something I never suspected was possible). The lack of pins to attach the rubber band to then resulted in the rest of the redesign.
Here I'm showing how the liftarms protruding from the top of the barrel can be pulled back to release the pressure on the bricks in the chamber, allowing them to slide out easily
One more shot of the gun, and we're on to...
Initial work consisted of printing off a 1:1 template, clearing up my room (fun), and then getting out all the Lego (notice a familiar face?) and making a mess...
Initial prototyping consisted of working out the best barrel design (notice how in my final design, the slits in the main barrels for the hammers are too wide - this stops anything getting stuck. It also managed to create an impression of curviness/roundness of the barrels, which improved the overall look)
These are some of the ways I tried to strengthen the barrels by rigidly connecting the top beam to the very bottom. The ideas here revolved around using a thinner-than-1M-beam going between the barrels (making it thin meant nothing would hit it on the way down), but in the end I decided to make the connection on the outside of the barrels, as seen in the final model. The filing down of the grey pins was done to provide a pin that was just long enough to secure the plates, as shown in picture three.
With a semblance of a hammer and bolt mechanism realised (see first photo), it was time to commit to the build by breaking up the Enfield (sadface) in order to convert the initial, multicoloured prototype into the beginnings of the real thing, using the now-available black bricks
And with that done, it was time to start work on the trigger mechanism. This turned out to be quite tricky, hence the multiple designs.
Finally, some back and forth on the front and back of the gun, and then suddenly....
It was done!
And after all that, it's time for...
THE BRICKUN BOOK REVIEW
So this is the latest in No Starch's run of gun books... and again, it's from someone we're all fairly familiar with! Jeff Boen, the author, is the man behind Brickgun.com, a website that greatly inspired me when I was starting out myself; I'm sure most of you are already familiar with it too.
The book's main attraction is the fact that all the models are incredibly realistic, in fact it seems Jeff has taken a completely opposite approach to me in terms of building: he's gone for form above function, I would normally reverse that. But that's not to say that the "function" part has been in any way diminished - four of the five guns in the book feature very efficient little mechanisms that make the gun "click" as the hammer falls, and allow the slide to be locked back, and so on... and then the fourth model is a very familiar rubber band gun.
Jeff starts the book with some text about the when, why and how he started building the models, giving some design history and a few insightful building tips - don't skip the theory, students!
Looking at the instructions themselves, the first thing to notice is that the guns are mostly made from normal bricks, with the occasional bit of technic thrown in, and this is reflected in the style of the picture - 3D, isometric and using plain shading to maximise "readability". There's a photorealistic rendering for each gun, though, at the start of each chapter, followed by the corresponding bill of materials (BOM). This is where I have probably my biggest gripe about the book - the BOMs are done twice for each model, once by text with the part name, quantity, description and colour, and once again, on the next page, with a picture of the part next to its quantity (which is how Lego themselves do their BOMs).
This, I think, creates a slight problem in that if you have a certain number of pieces already, and only want to buy the new pieces you need, then you would match the pieces you had to the pictures... and then find that you didn't actually know the part numbers for the pieces you still needed, because they're not listed on the picture BOM, only in the text-based one. However, it doesn't take much more effort to match the parts you have to their descriptions in the text BOM, so as I say - it's my biggest gripe, and it's actually not a particularly big one.
The guns though, are very well done, using some really ingenious techniques (I particularly like the transition from SOT to SNOT in the muzzle of the BG 22) and very efficient use of space (when I built guns this small, I usually ended up having to modify pieces, Jeff's managed to avoid this). The only critiques I can even begin to come up with are the lack of cross-bracing (something that I use a lot), and how some of the rubber bands are attached. However as these models are smaller and more "models" than "toys", the lack of cross bracing isn't such a big deal and as for the rubber bands... essentially what he's occasionally done is looped a band over parts with no discernible "hooking" bit to stop the band sliding off. I imagine this could create a problem with bands with a round cross-section, but if they're square then you should be fine.
For the four models with "clicking" mechanisms, Jeff's essentially taken the same mechanism and put it inside four different bodies. I actually fully approve of this, because while it's not as mechanically diverse initially, I think that this book is maybe aimed at the slightly less technical builders - who could benefit immensely from being shown an example of realising the same concept in different ways, which is an incredibly useful skill to learn.
The Mac-11 is the rubber band gun of the book, and again, the mechanism isn't overly complex, something I think is a good idea: after showing a young builder how to adapt a mechanism to fit in different guns, Jeff has gone ahead to show them a new mechanism, one that they can maybe tweak to put in their own models using the new skills he's provided them with. The fact that all the guns are fairly small means that these younger builders will still be able to afford to buy the bricks to build them, without having to live on cereal for a month.
All in all, I think Jeff and No Starch have done a really good job here; it's an excellent guide and a very worthwhile buy. Thanks Jeff!
You make the best lego guns ever jack.
I have attempted many times to make lego guns and have failed EPICLY. Please send info on the mech of the aks74u please please please please I need help I look up 2 you please reply to me I am at
Please help jack, I will thank you so much!