Heres the thing about the gun control disagreement between Lena and James:
They both have excellent, very personal reasons why they feel the way they do. This is a very important conversation for them to have as a serious couple, as it could be a significant measure of how compatible they are as a couple.
Lena owns a gun. Lena has a very good reason to own a gun. Her life is in danger almost constantly, and having been arrested at least once before probably doesn't give her much faith in the police to protect her, and now that she's on the outs with Supergirl she probably doesn't trust that SG will be so quick to come to her rescue next time. (I would also like to know when she used her gun to protect herself. It sounds like a story and we haven't seen it, so...)
Meanwhile, James has the complete opposite viewpoint. Carrying a gun would only endanger his life as a black man in today's America, and how many of his fellow black Americans have been murdered by guns? To him, guns are the problem, not the solution. He also has the long view-- of children having the right to go to school without fear of dying, etc.
I would also argue that Lena is the more pivotal argument, rather than the gun manufacurer. He's easy to understand-- he wants to make money, and we don't expect him to change. But Lena? Lena, who cares about the greater good, who has only ever wanted to help people, and still owns a gun and believes in her right to own one?
She's the kind of person we're more likely to come up against in our own lives, and therefore far more impacting than a single scene with a 'stache-twirling cartoon of a Mr. Moneybags trope.
So, maybe James lets the subject slide the first time it comes up at CatCo. I get it-- he likes Lena, they're in a good place, he doesn't wanna chuck it out the window. Not to mention, it comes completely out of left field that Lena Luthor to share an opinion with the cling-to-your-guns conservatives, so he's probably reeling a little bit.
But even after he regains his bearings, he can't get it out of his mind. So he comes back to Lena armed with an argument the show itself has primed itself for:
"The government expects aliens to register themselves as possible threats, but you don't think we should register weapons that are specifically designed to kill people?"
Lena blinks in surprise, then creases into a mix of confusion and indignation. "I support gun registration, James. I acquired my handgun through legal means, and ensured it was registered with NCPD when I moved to National City. I take regular refresher courses on its use and care, and keep it secured when not on my person-- and yes, I have a registered concealed carry permit as well."
James doesn't know how to respond to that.
"I agree that we need better gun control measures, but I don't agree that outlawing guns for all private citizens is the solution. And I'm not speaking from a place of nostalgia for frontier americana, but from one of practicality. There will always be those who have access to guns, through legal means or otherwise, and people have a right to protect themselves in kind."
Maybe they go deeper than that, and explore that Lena only supports government oversight to an extent-- that ultimately, she doesn't trust the government to decide who deserves a gun and who doesn't. Or that she ascribes to a slippery slope mentality regarding gun control.
But they find some kind of middle ground where James is assuaged that Lena isn't advocating arming teachers in schools or using the terror watchlist in lieu of actual background checks, and Lena feels she's been heard and understood and that her boyfriend doesn't expect her to live defenseless when the entire world seems to want her dead.
And we think that's going to be it-- we get the bad guy and our inspirational speech or whatever, but then... our button scene is the CatCo office, late at night. James is still troubled when Lena walks in and finds him slouched in his chair. Their eyes meet, and we can feel the disruption in the bond between them as Lena wordlessly slides a slip of paper across the desk.
"What's this?" James asks.
"A receipt." Lena holds his gaze. "I surrendered my handguns to NCPD this morning."
Whatever James expected her to say, it's not that.
"I've been thinking about what you said. And while I still think you're idealistic, you have a point."
"You do too," he tells her, coming out from around the desk. "And I'm sorry I tried to minimize that. The threats you face are real, and you deserve the right to defend yourself."
To James' surprise, Lena lifts one shoulder in a shrug. "The kinds of enemies I have lately, a gun won't help me. Me giving up my personal weapons isn't going to fix anything, but... it has to start somewhere, right? So why not with me."
James wraps her in a tight hug, and he can feel some of the tension bleed out of her as her arms circle his waist. She leans into him with a sigh. "You're amazing, you know that?"
"I'm selfish." Her voice sounds thin against his chest.
"What?" James pulls back in confusion. "This is the exact opposite of selfish."
"You want to know what actually prompted me to do something about it?" Lena asks. "It wasn't what you said about children going to school, or police brutality... I make donations to gun control lobbies, but the hundreds of people who've already died from gun violence this year weren't enough for me to make any changes to my own life."
James regards her softly. "Then what was it?"
"The cult you saved Tanya from-- they had guns. Probably through the same proper channels I did. And they used them to shoot you in the head."
Green eyes sparkle with tears, filled with self-reproach and anger. "That's what made it real for me. So apparently I only care when it affects me personally. I'm that person."
"Hey," James interjects, taking her hands in his. "You're one of the kindest people I know, and you've done as much good for this city as Supergirl. Honestly I don't know how you care as much as you do-- about everything."
Lena doesn't look convinced. James cups her cheek, willing her to hear him.
"You are an inspiration to me, Lena Kieran Luthor. And I'm lucky to know you."
Lena's right, that change won't happen overnight. But now with her help... maybe it'll start.