Every video I’ve seen on this shows only some PARTS of the gun can be printed. And the barrel and firing pin are not among them.
Please don’t fall into the trap of calling a semiautomatic weapon a Machine Gun.
An Full Automatic continues to fire so long as the trigger is held down functioning like a machine gun until all rounds are spent.
This is not the AR-15. The AR-15 is a Semiautomatic, every time the trigger is pulled it fires 1 round.
If it get to a point where we have to BUILD OUR OWN, we’re in big trouble.
I’m in when they can print up an M2.
2) That is not even a complete AR-15. It is only the lower receiver, the part that holds the trigger and stands between the barrel/upper receiver/bolt assembly and the shoulder stock. The barrel, upper receiver, trigger group, bolt, bolt carrier, and charging handle all have to be manufactured by conventional means (milling machine).
3) On my blog, I go into the technical aspects of this: "Innovation Beats Gun Control, Every Time."
Additive manufacturing short circuits this and does an end around both big industry and big government. It puts power back into the ordinary citizen's hands in ways that it hasn't been since the industrial revolution. This is the genie that is out of the bottle.
I’ve never seen an AR-15 machine gun.
Guess there will be a ban on 3d printers.
I try to explain to people that guns are a 14th century technology - it isn’t splitting the atom. Gunpowder is made from very abundant minerals.
You can build a gun if you have a semi decent machine shop, like a place that mills engine parts or bores cylinders. I think the guy who made the MAC-10 worked out of a quonset hut.
Like passing a law against guns will make them go away. The mob will make them.
perhaps the government will mandate do not duplicate codes like the forced adobe and scanner makers.
One need only engineer the gun specifically to deal with the recoil and shock of igniting the primer. The barrel and chamber will still have to be made of steel. The rest of the gun could be made of plastic and off the shelf parts that are legal for purchase now.
OK, there’s lots of fretting about the barrel issue.
Right now, it is nowhere near cost-effective to “print” a barrel. But making a barrel isn’t some deep, dark witchcraft. The machines to do this aren’t new.
For people who wonder “How DO you make a barrel?” Watch this video:
https://www.youtube.com/watch?NR=1&v=kvnKSfDUCWY
OK, the rifling machine you’re watching there, painted in bright green, is an old Pratt & Whitney “sine bar” rifling machine. The name of “sine bar” is taken from the bar that controls how fast/tight the twist of the rifling is. If you freeze the video at 2:29, and then allow it to run forward to 2:36, I can describe what’s going on.
The green bar on a slant to the axis of the machine is a “sine” bar. Under that bar, which is set at an angle to the longitudinal axis of the machine, is a slot. There is a follower on the blue cross-slide under the green bridge/sine-bar that pulls the blue cross-slide across the long axis of the machine, and that linear motion of the blue slide is converted into a rotation of the cutting tool as it runs down the barrel.
The cutting tool is a wee little scraper in the head end of the rod that keeps poking it’s head out of the end of the barrel. They’re set up to cut on only one direction of the stroke, typically on the pull.
The barrel is rotated by a fixed about in those chucks every time the cutter emerges from the end of the barrel.
The cutter’s engagement into the wall of the barrel is increased every so many passes through the each groove in the barrel - but the advance in the depth of cut is by like a tenth of a thousandth per increase. Increasing to cut something like a thousandth instead of a tenth would result in too much material in the bore for the cutter to clear.
OK, lots of you guys who might shoot guns, but not work on guns or in machine shops are looking at that machine and saying “How old is this technology? How old is that machine?”
You guys sitting down? You might want to.
That machine, the P&W sine-bar rifling machine, was first made in the 1890’s.
Not only before WWI - but a pretty long time before WWI.
The best shooting barrels in the country are made on machines like this. Krieger, Bartlein and other single-point-cut barrels are made on P&W machines like this *today* - right now.
OK, what’s my point?
Someone with a lathe and some get-up-n-go can accomplish the same thing on an old lathe. I’m not going into tremendous detail how to do it, because it would require a long write-up, but suffice to say I could make a machine that would rifle a barrel in the same manner on some old, cheap lathe like a South Bend 13” swing machine, especially one with a longer bed. The leadscrew would be disconnected from the headstock gears and the spindle in the headstock would be used to hold the barrel. The leadscrew would be driven by a servo motor. The rotation of the spindle (with the barrel through it) would jump from groove to groove, then a sine-bar mechanism mounted out on the end of the bed would control the rotation of the cutting tool. The advance/retract of the cutting tool would be done by powering the leadscrew with the servo motor.
The same lathe could be used to deep-hole drill the barrel, then ream it.
Harry Pope used to make barrels on a modified lathe with a single point cutter.