Can someone with felony charges own a gun or buy a gun?

It is not legal for him to have or being around guns.

Absolutely NOT.

Typically no, but depends on the state he lives in and the age of the weapons.

No, it's illegal for a convicted felon to own a gun in Missouri.

It is legal for your brother to own or possess a gun. Persons ineligible to possess firearms and ammunition in California include Persons Convicted of Felonies or Other Specified Crimes. Any person who (a) has been convicted of a felony under the laws of the United States, the State of California, or any other state, government, or country, or (b) is addicted to any narcotic drug may not own or have in his or her possession, custody, or control any firearm. (Penal Code 12021(a).) It is unlawful for any person who is prohibited from possessing firearms, to possess ammunition. (Penal Code 12316(b).) A felony conviction refers to a conviction of an offense that can only result in felony punishment under California law, or any sentence to a federal correctional facility for more than 30 days, or a fine of more than $1,000, or both. (Penal Code 12021(f).) Any person convicted of any of the following crimes specified in Penal Code sections 12001.6 and 12021.1, whether as a felony or misdemeanor, may not lawfully possess or have under his or her custody or control any firearm: Murder or voluntary manslaughter. Mayhem. Rape. Sodomy or oral copulation by force, violence, duress, menace, or threat of great bodily harm. Lewd acts on a child under the age of 14. Any felony punishable by death or imprisonment in the state prison for life. Any other felony in which the defendant inflicts great bodily injury on any person, other than an accomplice, that has been charged and proven, or any felony in which the defendant uses a firearm which has been charged and proven. Attempted murder. Assault with intent to commit rape or robbery. Assault with a deadly weapon or instrument on a peace officer. Assault by a life prisoner on a non-inmate. Assault with a deadly weapon by an inmate. Arson. Exploding a destructive device or any explosive with intent to injure or murder. Exploding a destructive device or any explosive causing great bodily injury. Robbery. Kidnapping. Taking of a hostage by a state prison inmate. Attempting to commit a felony punishable by death or imprisonment in the state prison for life. Any felony in which the defendant personally used a dangerous or deadly weapon. Escape from a state prison by use of force or violence. Assault with a deadly weapon or force likely to produce great bodily injury. Any attempt to commit any of the above crimes other than an assault. Assault upon a person with a firearm. Shooting at an inhabited dwelling house or occupied building. NOTE: This offense is committed even though no person was actually inside the specified structure at the time of the shooting. Drawing, exhibiting, or unlawfully using any handgun or firearm in a rude, angry, or threatening manner in the presence of a peace officer regardless of whether the firearm is loaded. Carjacking. Two or more convictions for drawing or exhibiting any firearm in a rude, angry, or threatening manner in the presence of another regardless of whether the firearm is loaded. Persons Convicted of Misdemeanor Violations of Specified Offenses Any person convicted of a misdemeanor violation for one or more of the following offenses is prohibited from owning, possessing or having under his or her custody or control any firearm within 10 years of the conviction (Penal Code 12021(c)(1)): Threatening public officers and employees and school officials. (Penal Code 71.) Threatening certain public officials, appointees, judges, staff or their immediate families. (Penal Code 76.) Possession of a deadly weapon with intent to commit an assault (Penal Code 12024.) Possession of a deadly weapon with the intent to intimidate a witness. (Penal Code 136.5.) Unauthorized possession/transportation of a machinegun. (Penal Code ? 12220.) Threatening witnesses, victims, or informants. (Penal Code 140.) Obstructing or delaying an officer or emergency medical technician and removing or attempting to remove a fire

As a general rule NO, his ownership or possession of firearms under the conditions you state is a federal crime, and it the current atmosphere would be very likely to be prosecuted to the full extent of the law. Does he really wish to return to prison?

Charges or convictions? There is a difference. Normally, someone who has been convicted of a felony cannot own, possess, or use a firearm unless those rights have been restored by law.

Depends whether those charges ended in convictions.