Building a Full-Auto Gauss Gun 285
Okian Warrior writes "Adding to the 3-D printed gun/rifle controversy, Delta-V Engineering built a Full-auto Gauss gun (aka 'machine gun'), capable of firing 15 steel bolts from its magazine in less than two seconds. At 3% the muzzle energy of a .22, it's still in the prototype stage. Bullets are made from turned-down nails, and the gun uses no chemical propellants. The builder has posted the design notes online. Video of the gun in action is pretty interesting."
3% velocity (Score:5, Informative)
okay, a .22 averages around 1,120 f/s [wikipedia.org]. 3% of that is 33.6 feet per second. That translates to around 23 MPH. Yes, I can see how this highly dangerous weapon might add to the controversy of 3D printed guns. It is only slightly slower than an olympic sprinter running at full tilt [hypertextbook.com].
Re:Sensationalist summary at all? (Score:5, Informative)
Not only that, but this isn't even legally a "gun" under U.S. law.
Re:Sensationalist summary at all? (Score:5, Informative)
Why would you think that?
You can make a fully automatic submachine gun of the open bolt design out of stuff you can find at home depot.
Re:3% velocity (Score:5, Informative)
If you RTFA, you'll find that the muzzle energy is 3% of that of a .22, not the velocity. The velocity is about 40m/s, or about 90MPH.
Re:3% velocity (Score:5, Informative)
Neither, considering that the article mentions 3% muzzle energy of an .22 LR which is different than the muzzle velocity. Proof: this picture here [puu.sh]
Re:Sensationalist summary at all? (Score:5, Informative)
Re:Smaller projectiles? (Score:2, Informative)
From "The Maths" section of the builder's website [deltaveng.com]:
"The most frequent comment I get on my coilguns is that I should use a lighter projectile to improve performance. This equations [sic] shows why that suggestion is wrong. It’s counter-intuitive, but for a fixed power and distance (e.g. fixed capacitor bank and coil), a lighter projectile will gain less muzzle energy than a heavier one."
Re:Sensationalist summary at all? (Score:5, Informative)
"expel a projectile by the action of an explosive"
That part.
Re:Sensationalist summary at all? (Score:4, Informative)
Correct me if I'm wrong, but when using this device, a bullet, from a loaded cartridge, gets propelled down a barrel by action of the explosive powders in the cartridge.
No. It does not.
http://en.wikipedia.org/wiki/Coilgun [wikipedia.org]
A series of magnets propels a projectile.
There is no explosive powder. There is no explosion.
Re:3% velocity (Score:4, Informative)
According to Wikipedia, [wikipedia.org] a BB gun has about 18% of the muzzle energy of a .22. And this thing is 1/6 the strength of that. We're getting down to Lego [youtube.com] territory.
Re:Sensationalist summary at all? (Score:5, Informative)
Not really.
Closed bolt machineguns require fairly precise contrivancnces to make the firing pin strike at the right time during the cycle of function. This includes most Automatic Rifles and Submachineguns that must have select fire capability (semi, burst, full. for example). In some cases, precise headspace is a factor also (how close the bolt face is to the breach when the firing happens), or the machinegun must have a variable headspace. The M2 .50 cal has variable headspace AND timing. Semi autos aren't just fully autos with something to stop them for this reason.
If an M16 (or M4) was allowed to go full auto without a "disconnector", the hammer would be allowed to fall too early in the cycle. Best case would be failure to fire (cartridge not fully seated on bolt face yet), worst case would be an out-of-battery detonation with hot brass fragments flying out the ejection port.
Open bolt machineguns, (M60, M249, M240, et al) are more like as you describe. The operating parts (including the bolt) would be more than happy to run away until the belt ran out if it weren't for that damn sear holding them back. Open bolt machineguns are not to be fired semi-automatically. Even purposely single-shooting them (unless only loading single rounds) wears down the sear and can lead to a runaway gun.