I think he's a great actor. I love his films. That being said, he is most definitely a "prohibited person" when it comes to guns. Agree or disagree, you are putting both him and yourself in legal jeopardy by handing him a gun.
From the world most trustworthy news source (wikipedia):
"From 1996 through 2001, Downey was arrested numerous times on drug-related charges including cocaine, heroin and marijuana[17] and went several times through drug treatment programs unsuccessfully, explaining in 1999 to a judge: "It's like I've got a shotgun in my mouth with my finger on the trigger, and I like the taste of the gun metal."[18] He explained his relapses by claiming to have been addicted to drugs since the age of eight, due to the fact that his father, also an addict, had been giving them to him.[18][19]
In April 1996, Downey was arrested for possession of heroin, cocaine and an unloaded .357 Magnum handgun while he was speeding down Sunset Boulevard. A month later, while on parole, he trespassed into a neighbor's home while under the influence of a controlled substance and fell asleep in one of the beds.[20][21] He was sentenced to three years of probation and required to undergo compulsory drug testing. In 1997, he missed one of the court-ordered drug tests and had to spend four months in the Los Angeles County jail.
After Downey missed another required drug test in 1999, he was arrested once more. Despite Downey's lawyer, John Stewart Holden, assembling for his client's 1999 defense the same team of lawyers that successfully defended O.J. Simpson during his criminal trial for murder,[18] Downey was sentenced to a three-year prison term at the California Substance Abuse Treatment Facility and State Prison in Corcoran, California (a.k.a. "Corcoran II"). At the time of the 1999 arrest, all of Downey's film projects had wrapped and were close to release, with the exception of In Dreams, which he was allowed to complete filming. He had also been hired for voicing "The Devil" on the NBC animated television series God, the Devil and Bob, but was fired when he failed to show up for rehearsals.[22][23]
After spending nearly a year in California Substance Abuse Treatment Facility and State Prison in Corcoran, California, Downey, on condition of posting $5,000 bail, was unexpectedly freed when a judge ruled that his collective time in incarceration facilities (spawned from the initial 1996 arrests) had qualified him for early release.[5] A week after his 2000 release, Downey joined the cast of the hit television series Ally McBeal, playing the new love interest of Calista Flockhart's title character.[24] His performance was praised and the following year he was nominated for an Emmy Award in the Outstanding Supporting Actor in a Comedy Series category and won a Golden Globe for Best Supporting Actor in a mini-series or television film.[25][26] He also appeared as a writer and singer on Vonda Shepard's Ally McBeal: For Once in My Life album, and he sang with Sting a duet of "Every Breath You Take" in an episode of the series. Despite the apparent success, Downey claims that his performance on the series was overrated and that, "It was my lowest point in terms of addictions. At that stage, I didn't give a **** whether I ever acted again."[14] In January 2001, Downey was scheduled to play the role of Hamlet in a Los Angeles stage production directed by Mel Gibson.[27]
Before the end of his first season on Ally McBeal, over the Thanksgiving 2000 holiday, Downey was arrested when his room at Merv Griffin's Hotel and Givenchy Spa in Palm Springs, California was searched by the police, who were responding to an anonymous 911 call. Downey was under the influence of a controlled substance and in possession of cocaine and Valium.[28][29] Despite the fact that, if convicted, he could face a prison sentence of up to four years and eight months, he signed on to appear in at least eight more Ally McBeal episodes.[30]
In April 2001, while he was on parole, a Los Angeles police officer found him wandering barefoot in Culver City, just outside Los Angeles. He was arrested for suspicion of being under the influence of drugs, but was released a few hours later,[31] even though tests showed he had cocaine in his system.[32] After this last arrest, producer David E. Kelley and other Ally McBeal executives ordered last-minute rewrites and reshoots and dismissed Downey from the show, despite the fact that Downey's character had resuscitated Ally McBeal's ratings.[33] The Culver City arrest also cost him a role in the high-profile film America's Sweethearts,[32] and the subsequent incarceration forced Mel Gibson to shut down his planned stage production of Hamlet, as well. In July 2001, Downey pleaded no contest to the Palm Springs charges, avoiding jail time. Instead, he was sent into drug rehabilitation and put on a three-year probation, benefiting from the California Proposition 36, which had been passed the year before with the aim of helping nonviolent drug offenders overcome their addictions instead of sending them to jail.[5][34]"