United States v. Miller, 307 U.S. 174 (1939)

[gejohnston]

3. Well regulated means well equiped.

to answer your question, almost any handgun, bolt action rifle, any semiautomatic or automatic weapon. The Walther GSP, a target pistol used in the World Cup and Olympics, probably not protected while a select fire assault rifles would be protected. The reason for the expensive tax stamp and registration instead of a ban, because the sponsors of the bill thought it would be struck down. The "collective right" concept did not exist until recently, and certainly would not be in the BoR.