[Daedalus]

This is a question I have been wondering.

Why is it that so many companies can make AR15 rifles and sell them for profit? Is there no patent on the design? Does it have something to do with the fact that the military adopted the design and it becomes "Public Domain"? Is this why 1911 copies are so plentiful as well?

[Harry Tuttle]

yep, Stoners design was bought by armalite and the military open sourced it to manufacturers

some stuff like the M4 designation is owned by Colt

[Daedalus]

Is that practice still done? If so what does this mean for, say, the XM-8 if it is adopted?

[BryanP]

Patents expire as well. Anyone can make a 1911 or a Hi Power, for example. Patents aren't like copyrights where Disney et al. goes in and buys themselves a few senators to extend it 20 years more every 20 years.

[4v50 Gary]

Yep, after a while, patents expire and it's fair market. Hence the Ruger 10/22 was copied by AMT (and I think someone else).

[Nightcrawler]

Also, the vast majority of AR-15 clone manufacturers don't actually manufacture them. They do the final machining, perhaps, they assemble them, probably, and sometimes do the final finishing. But the actual parts are often made in bulk by a variety of subcontractors. This is why little "mom & pop" companies can make their own AR-15 clones; all they have to do is put them together and plop down their rollstamp.

Colt is, as far as I know, the only US company that actually makes all of its parts for all of its rifles.

[Dave Markowitz]

Note that the only company that can call their rifle an "AR-15" is Colt, which owns the trademark. That's why Bushmaster are marked "XM-15" and ArmaLites are marked "M-15." (The original ArmaLite company sold the TM rights to Colt long ago. When Eagle Arms bought up the assets of the old ArmaLite, they got the "ArmaLite" TM, but not "AR-15.")