People unfamiliar with shooting sports sometimes fail to realize the physicality of getting a bullet to go where you want it to. In the brief but finite amount of time that the bullet is accelerating down the barrel, the tiniest movement of the gun can produce enormous changes in its trajectory, and the farther away your target is, the bigger the potential error introduced by anticipating recoil or jerking the trigger.
Like many problems this one is much easier to fix with what you can quantify, which is where this DIY rifle accelerometer can come in handy. There are commercial units designed to do the same thing that [Eric Higgins]’ device does but most are priced pretty dearly, so with 3-axis accelerometer boards going for $3, rolling his own was a good investment. Version 1, using an Arduino Uno and an accelerometer board for data capture with a Raspberry Pi for analysis, proved too unwieldy to be practical. The next version had a much-reduced footprint, with a Feather and the sensor mounted in a 3D-printed tray for mounting solidly on the rifle. The sensor captures data at about 140 Hz, which is enough to visualize any unintended movements imparted on the rifle while taking a shot. [Eric] was able to use the data to find at least one instance where he appeared to flinch.
On today’s episode of ‘this is a really neat video that will soon be demonetized by YouTube’ comes this fantastic build from [John]. It is the Golden Gun, or at least it looks like a Golden Gun because it’s made out of melted down brass casings. It’s a masterclass demonstration of melting stuff down and turning a thirteen-pound blob of metal into a two-pound precision machined instrument.
This build began by simply cutting a wooden block, packing it in sand, and melting approximately 1425 shell casings of various calibers in a DIY furnace. The molten brass was then simply poured into the open mold. This is standard yellow brass, with about 70% copper and 30% zinc. There’s a bit of aluminum in there from the primers, and the resulting block isn’t terribly great for machining. [John] says this could be fixed by adding a few percent of lead to the melt. To all the jokesters suggesting he add some unfired bullets to the melt, don’t worry, we already have that covered.
The machining went as you would expect it would with a large mill, but there are a few things that made this entire video worthwhile. For some of the holes, [John] had to square up the corners. The simplest and easiest way to do this is to break out a file. This is brass, though, and with some steel chisels hanging around the shop your mortise and tenon skills might come in handy. With the very careful application of force, [John] managed to put corners on a circle with a standard wood chisel. A bit later in the build video, a few more sharp corners were created by shoving a broach in the mill and jamming it down into the work.
When it comes to machining builds, this is high art. Yes, it’s the same as building an AR-15 out of a few hundred soda cans, but this one is made out of brass. It looks just great, and that final polish turns the entire project into something that looks like it’s out of a video game. Simply amazing.
Yes, it has its limits, but every new technology does, especially totally home-brew builds like this. The aptly named [NSA_listbot] has been putting a lot of work into his railgun, and this is but the most recent product of an iterative design cycle.
The principle is similar to other railguns we’ve featured before, which accelerate projectiles using rapidly pulsed electromagnets. The features list in the video below reads like a spec for a top-secret military project: field-augmented circular bore, 4.5kJ capacitor bank, and a custom Arduino Nano that’s hardened against the huge electromagnetic pulse (EMP) generated by the coils. But the interesting bits are in the mechanical design, which had to depart from standard firearms designs to handle the caseless 6 mm projectiles. The resulting receiver and magazines are entirely 3D printed. Although it packs a wallop, its cyclic rate of fire is painfully slow. We expect that’ll improve as battery and capacitor technology catches up, though.
It may not be a “phased plasma rifle in the 40-watt range,” and it doesn’t even use plasma in the strict definition, but it’s pretty cool nonetheless. It’s a propane-powered bottle-launching rifle, and it looks like a lot of fun.
[NighthawkInLight] sure likes things that go pop, like his watermelon-wasting air-powered cannon and cheesy-poof pop gun. This one has a little more oomph to it, powered as it is by a propane torch. The principle is simple: fill a soda bottle with propane, ignite the gas, fun ensues. The details are a little more subtle, though, and allowances need to be made to keep back pressure from preventing the projectile from filling with fuel. [NighthawkInLight] overcomes this with some clever machining of the barrel. The final production version in the video below is needlessly but delightfully complex, with a wooden stock and a coil of clear vinyl tubing helical plasma accumulator before the barrel; the last bit is just for show, and we have to admit that it looks pretty good.
Unless you count the pro tip on using CPVC pipe to make custom fittings, this one is nothing but fun. But we don’t have a problem with that.
This coilgun started as a stock Airsoft rifle. The stock weapon cost about 40€ (just over $50), but we think it was well worth it since it provides plenty of room for all the coilgun components and solves most of the mechanical issues of the build like a body that is comfortable to hold, a trigger, etc.
The clear tube which serves as the barrel (the same setup as we saw in this coilgun guide) is protected by three stainless steel barrels which surround it. They each host a laser diode which results in a Predator-style aiming mechanism that is shown off in the video after the break. There’s even a night vision system that uses IR leds and a viewfinder attached to the stock.
A camera flash is scrapped for the transformer inside. This acts as the voltage generator, charging up a few capacitors. It seems to have no problem generating enough juice to work well, despite the fact that it’s only being powered from two AA batteries mounted in the magazine.
Just in time for your garden’s carrot harvest [Lou] shows us how to make a carrot firing rifle. It’s cheap, easy, and quick. If you’ve got 15 buck and 15 minutes you can have one to call your own.
The loading method is quite easy. Shove a carrot in the muzzle as far as it will go, then cut of the excess. Finish up by using a ramrod to push the carrot stub the rest of the way into the barrel. Once you’ve gnawed down the rest of the carrot nub and connected a compressor hose to the rifle you’re ready to do some damage. The video after the break shows a carrot fired all the way through a cardboard box, and penetrating a gallon jug of water.
[Lou] uses CPVC for the project. It takes just a few lengths of pipe, pipe fittings, a valve, and a threaded metal compressor fitting. After gluing everything together he threads the compressor attachment in place and heads to the firing range.
Ar15.com user [HaveBlue] has been working for some time on a 3D printed lower receiver, and now reports that the parts are fully working. Using a Stratasys 3D printer from the 90’s [HaveBlue] managed to spin out a modified version of an already available model from cncguns.com. He strengthened the holes for the takedown lugs, which hold the upper and lower halves of the rifle together. Strengthened the bolt hold lugs, which when the magazine is empty lifts a lever assembly that catches the bolt as it springs back to push another round into the chamber. and added an integral trigger guard AKA the bar that surrounds the trigger.
Legally this print is a veritable gauntlet of state and federal regulations. At least in the US. The lower receiver is the part of the rifle that holds the spring and pins that operate the rifle’s trigger safety and hammer assembly, hold the magazine in place, and mount the buttstock/return spring tube. The other key point about the lower receiver is that it contains the primary traceable identification markings, the serial number. All of the parts that are contained within the lower receiver can be ordered online (this varies state to state). In fact, every single other part of the rifle can be bought and sold freely. The only component of the rifle that can not be ordered online, and requires a background check at a gun store, is the body of the lower receiver (we have to keep saying that this varies state to state). Typically laws allow though for the manufacture of this part without a serial number so long as it is never sold to another individual (again, state laws vary widely).
There is some more info on the build at [HaveBlue]’s website here and here, but it is currently down. This sort of steps up 3D printing past the nerf gun stage, but we have seen shot gun and pistol hacks.