What a can of worms...
Used to be, you knew where you stood. Back in common law England, and the early colonies, the felonies were
1. Homocide
2. Rape
3. Robbery
4. Burglary
5. Grand Larceny
6. Arson
7. Possibly kidnapping (not sure - it definitely is a felony now).
8. Mayhem (or maiming)
I think that's it. Now, there's humpteen thousand federal felonies, not to mention various and sundry state felonies. Embezzlement can be a felony now, though I don't think it was at common law - I need to find a history of the law book and look at it. People have always been ignorant of the law at their own peril - in other words, not knowing something was a crime is/was not a defense. This is still true, but unfortunately, it exponentially more difficult to try to figure out what's illegal. Not all state crimes are in the "Crimes" title to the state statutes - they'r scattered throughout. Ditto for federal - many crimes are scattered throughout the federal code and federal regs even. Basically, the feds have probably made walking and chewing gum at the same time a felony, but we just don't realize it yet, because they haven't charged anyone with it yet - they'll exercise their "prosecutorial discretion" to charge someone with this heineous crime (W&CG) whenever the defendant is a political opponent, or disliked by society, which scores a political victory for the prosecutor. It's absurd. Making possession of a part of any weapon a crime, whether misdemeanor or felony, is totally unconstitutional - my BP is raising just thinking about this. The government can kiss my ass. I don't care whether I'm in NY or Kalamazoo - I will put any freaking upper on any freaking receiver that fits - consequences be damned. I'm ready to go to jail to fight such a frontal assualt on citizens' right to KEEP and BEAR ARMS - what part is unclear, you idiots in government? Gotta go before my temples explode.