I've heard it several times on Reddit that Reagan was a staunch supporter of unregulated gun control until the Black Panthers started arming themselves and that at that point, Reagan pushed for stricter gun control laws. And furthermore that this was a result of his racist attitudes about Black Americans owning guns. Is this true?
Until someone can provide more information specifically regarding Ronald Reagan's motivations, a similar question was asked about the gun control lobby in general on the passage of the Milford Act by u/EscapeAndEvadeSteve that does include a quote by Regan:
Non-historian but librarian here with a personal interest in Bobby Seale, so... hopefully this'll scratch the itch until a Reagan expert can get on the line.
I think it's uncontroversial to say that that the passage of Section 12031 was in response to the Black Panthers. That said, I think that it's very easy to overstate Reagan's role in this and see it as some sort of explicitly racist intent here, particularly given his later turn against gun control.
California AB 1591 (a.k.a. the Mulford Act) was introduced in April of 1967 by Rep. Don Mulford after a few Panther-related incidents in Contra Costa County. On April 1st, the police killed Denzil Dowell, a 22-year old black man, in Richmond, CA (near Oakland). Only a few months prior, Huey P. Newton and Bobby Seale had founded the Black Panther Party for Self-Defense a few miles west in Oakland and had been organizing armed patrols to police the police. Newton was Dowell's family reached out and requested assistance from the Panthers.
The Panthers obliged, held armed rallies in Richmond, and engaged in community outreach efforts to encourage Black residents to embrace firearms in order to oppose government and police oppression. They also entered a police station armed demanding justice. These are the actions that led Mulford to introduce his legislation a few weeks later. Mulford painted with a broad brush, naming the Minutemen, the KKK, and the American Nazi Party as well as the Panthers. But this legislation was very much a result of the Panthers' actions.
But to back up just slightly, gun control was in the air in 1967. Coming up for debate on the same day as Mulford's bill were four bills that came from the Assembly's two-year study on the matter: AB 1323, 1324, 1325, and 1326. These regulated handgun purchases from out of state, larger caliber weapons, and machine gun parts. So it's not like gun control just appeared.
Anyway, the Panthers recognized that they were being targeted explicitly, and when Mulford's bill came up for debate on May 2nd, 1967, a couple dozen armed Panthers pushed the sargent-at-arms out of the way and forced their way into the chambers. Bobby Seal gave a speech detailing America's racist legacies and urging black people to arm themselves against the terror of the state.
To be clear, waiving a loaded gun around in the Capitol was not a felony offense at the time -- Newton knew the laws better than anyone. But it was seen as an attempt at intimidation (Mulford called it out as such on the floor), and it shook up the legislators. Now, in a funny coincidence was Reagan was right outside the capitol -- about to have a picnic lunch with 30 elementary school children for a photo op -- when the Panthers walked by him on the way out. So the event was well reported on, and you can imagine the hoopla this caused. (I've included links to contemporaneous news articles at the end.) Because of the Capitol incursion, the Mulford Act quickly became fast-tracked with bi-partisan support.
So where does Ronald Reagan fit into all this? While the executive branch had supported the drafting of the legislation through the actions of Attorney General Thomas C. Lynch, Reagan personally wasn't really ahead of it. This was, up until the debacle at the Capitol, much more of an Oakland story than a California story. But since Reagan was there when it happened, the press asked him what he thought of it as the armed Panthers were leaving. And he said "there's no reason why on the street today a citizen should be carrying loaded weapons... Americans don't go around carrying guns with the idea of using them to influence other Americans."
Prior to this Reagan had not said a whole lot about gun control as a political issue. Remember, he'd only been on the job for a couple months. Prior to that his main political gig was stumping for Barry Goldwater. As far as I can tell looking back on those speeches, guns simply weren't on the table as an issue. Granted, both he and Goldwater were shooters and lifelong NRA members. But the 1967 NRA was very different than what the NRA would become 20 or 30 years later. The NRA supported the Mulford Act, along with a number of other laws that were at the time called "responsible gun ownership." Barry "I am the NRA" Goldwater himself was critical of the availability of semi-automatic rifles which would seem absolutely crazy in today's political environment.
The Mulford Act Passed easily in the Assembly and unanimously in the Senate. Because of the very obvious Black Panther connection, a number of Black Assembly members were asked about their impressions. Willie Brown said that while he supported the bill, he was skeptical of Mulford's timing, stating that Mulford had previously opposed such legislation "until Negros showed up in Oakland -- his district -- with arms." (So I wonder if this got telephoned into Reagan over the years...) Leon Ralph saw the bill as being aimed at the KKK. Bill Greene was happy that the Panther incident catalyzed the passing of the law.
So... I know this didn't tell you a whole lot about Reagan, but I think that's because Reagan just wasn't a pivotal figure in the whole thing. Which probably says something in and of itself.
If you want to dig through seven hundred pages of correspondence and debate relating the the Mulford Act, that is available at: http://publicfiles.firearmspolicy.org/mulford-act/california-ab1591-1967-mulford-act-bill-file.pdf
If you would prefer an excellent, excellent short (40p) summary of California's attempts to disarm the Black Panthers, you'll probably enjoy Cynthia Leonardatos' "California's Attempts to Disarm the Black Panthers," which appeard in the San Diego Law Review, and you can find here: https://digital.sandiego.edu/cgi/viewcontent.cgi?article=3267&context=sdlr
Cheers!