In Canada, a 3D-Printed Rifle Breaks On First Firing

Not all 3-D printed guns can encounter the smooth, uneventful success of Cody Wilson's Liberator; Daniel_Stuckey writes with this excerpt: "A Canadian has just fired the first shot from his creation, 'The Grizzly,' an entirely 3D-printed rifle. In that single shot, CanadianGunNut (his name on the DefCad forum), or "Matthew," has advanced 3D-printed firearms to yet another level. Sort of: According to his video's description, the rifle's barrel and receiver were both damaged in that single shot."

Re:I still see a market ....

[Penguinisto]

Heh - what else did they expect? Rifles keep pressure for longer periods of time (as the bullet travels down the longer barrel), increasing the chance for materials failure. Cheap plastic is not an option here, campers.

7,000+ psi for a .22LR is nothing to screw around with for the relatively sustained period of time the bullet travels down the barrel (let alone the 65,000+ psi you can generate in, oh, a .338 Win Mag.)

Big surprise

[cold fjord]

Rifle cartridges tend to have quite a bit more power than pistol cartridges.

Chamber pressure:

Rifle: 7.62x51mm maximum pressure 415 MPa / 60,191 psi
Rifle: 5.56x54mm maximum pressure 430 MPa / 62,366 psi
Pistol: .45 ACP maximum pressure 140 MPa / 21,000 psi
Pistol: 9x19mm maximum pressure 235 MPa / 34,084 psi
Pistol: 9x17mm maximum pressure 148 MPa / 21,500 psi

IIRC, the 9x17mm (.380) was used in some earlier 3D printed pistol tests with limited success.

Most people receiving medical treatment after being shot by a pistol will live. Mortality is much higher for those shot by a rifle.

Re:For a spy all you need is 1 shot

[interval1066]

Quite wrong. the .22 Long Rifle with hollow point, frangible, high velocity AND subsonic loads are all favored by assassins. The subsonic is especially accurate and if you're not shooting through armor or a helmet is going to take your target out if placed right. The load used by the Jackal (in the origiinal 1964 film) was a .22 LR exploder.

Re:Yet another low caliber 3D printed firearm

[Anonymous Coward]

There is a HUGE difference between a 22LR and a 5.56 or 223. Even if they are the "same calibur".
22LR, 36-40 grain, just over 1,000 ft/s
223 56 grain, just over 3000 ft/s

Re:Not to worry

[fuzzyfuzzyfungus]

Only a matter of time before the composites and process improve to the point where it will withstand these stresses.

Inconveniently, 3d printing techniques tend to make doing composites (properly) difficult. Extruder-based designs can use fiber reinforced feedstocks, if the usual parameter-fiddling is done properly; but doing that will mostly just serve to make the difference in strength between the continuous filament (relatively strong) and the bonds at the 'seams' where the newly extruded filament needs to fuse with the previous layer and any adjacent already-laid filament (absolute best case, these might be as strong as the continuous filament, almost always weaker, sometimes markedly so, depending on process control) even starker than it already is, since the reinforcement material won't extend throughout the part (as it does with injection-molded fiber reinforced parts).

Selective laser sintering, while classier, is similarly limited by the fact that the reinforcement material can't extend beyond the boundaries of the powder being sintered (and you can't make the powder particles larger without sending your resolution to hell).

(Now, in the hypothetical cyberpunk dystopian future, it might be possible to produce pre-woven carbon-nanotube/graphene/similar technobabble "sleeves" that would collapse down into easily concealable flat shapes (like a freshly ironed sock); but could be stretched over a simple form and impregnated with a polymer or epoxy to turn them into fiber-reinforced barrels quickly and with almost zero tools just before use, using the same basic techniques used for fiberglass or carbon fiber construction. Not obviously worth it vs. just smuggling normal guns; but it' be a cute trick.)

Re:I still see a market ....

[Will.Woodhull]

I was wrong, parent post is right. I just learned that the .22 "survival" carbine I had been thinking of has a steel barrel; the receiver and stock are nylon.

When I lived in more open country, I used to hunt with a .30-06 slide action and 2-7x scope. Now my hunting is in brushy country where shots over 100 yards are very rare, so I use a .30-30 lever action carbine with peep sights. I've never been in a situation where a .22 rifle would be of any use, so I never looked into that caliber.