Interesting milestone in open-source 3D printing over at Thingiverse: User crank has published a freely-downloadable magazine for the ubiquitous AR-15 rifle. As downloaded, crank’s magazine only holds five rounds, but a person with basic 3D modelling skills could modify it with little difficulty to produce a “high-capacity” magazine. I’m not sure what the current state of law on magazine size limits is, but prior to the sunset of the Federal Assault Weapons Ban (Wikipedia) in 2004, manufacture of an AR-15 magazine with a capacity of more than 10 rounds was an offense.
Crank reports that the magazine—which consists of a printable body, follower, spring, and baseplate—is fully functional, at least for a few rounds:
I have used this magazine, no jams or feed problems….. YET. It works, but be reminded it is only a printed ABS magazine. If you end up using a printed ABS mag spring be prepared for stress relaxation of the polymer over time, especailly [sic] if it is kept loaded over a long period of time.
As published and as printed by crank himself, I should emphasize, this magazine is (as I understand it) completely legal, and would’ve been legal even before the ban expired. But the file raises some interesting questions.