First, I hope your neighbor has learned his lesson. Drunk driving isn't something I take lightly.
This is for Indiana... not sure how much of this varies from state to state.
You can possess a cap and ball musket unless your felony conviction is for a crime listed under IC 35-47-4-5.
IC 35-47-4-5 Unlawful possession of firearm by serious violent felon
(1) murder (IC 35-42-1-1);
(2) voluntary manslaughter (IC 35-42-1-3);
(3) reckless homicide not committed by means of a vehicle (IC 35-42-1-5); (4) battery as a:
(A) Class A felony (IC 35-42-2-1(a)(5));
(B) Class B felony (IC 35-42-2-1(a)(4)); or
(C) Class C felony (IC 35-42-2-1(a)(3));
(5) aggravated battery (IC 35-42-2-1.5);
(6) kidnapping (IC 35-42-3-2);
(7) criminal confinement (IC 35-42-3-3);
(8) rape (IC 35-42-4-1);
(9) criminal deviate conduct (IC 35-42-4-2);
(10) child molesting (IC 35-42-4-3);
(11) sexual battery as a Class C felony (IC 35-42-4-8);
(12) robbery (IC 35-42-5-1);
(13) carjacking (IC 35-42-5-2);
(14) arson as a Class A felony or Class B felony (IC 35-43-1-1(a));
(15) burglary as a Class A felony or Class B felony (IC 35-43-2-1);
(16) assisting a criminal as a Class C felony (IC 35-44-3-2);
(17) resisting law enforcement as a Class B felony or Class C felony (IC 35-44-3-3);
(18) escape as a Class B felony or Class C felony (IC 35-44-3-5);
(19) trafficking with an inmate as a Class C felony (IC 35-44-3-9);
(20) criminal gang intimidation (IC 35-45-9-4);
(21) stalking as a Class B felony or Class C felony (IC 35-45-10-5);
(22) incest (IC 35-46-1-3);
(23) dealing in or manufacturing cocaine or a narcotic drug (IC 35-48-4-1); (24) dealing in methamphetamine (IC 35-48-4-1.1);
(25) dealing in a schedule I, II, or III controlled substance (IC 35-48-4-2); (26) dealing in a schedule IV controlled substance (IC 35-48-4-3); or
(27) dealing in a schedule V controlled substance (IC 35-48-4-4).
This was taken from the Indiana State Police website.
http://www.in.gov/isp/files/FirearmsFAQ.pdf