yeah just tell someone who's suicidal that they need to get a hobby
much better than letting medical professionals deal with the issue
its not about "locking him up" for life .. 51/50 holds are 72 hours and they can work from there to get you professional help
lol I didn't choose my words carefully at all but my main point is that you CAN work around Depression. If he is dissatisfied with living to the point of mentioning suicide there's a reason for that.
If he doesn't want to seek help you can either force it on him, which may or may not work, or get other people around him to try and do something about it.
"Expressing suicidal thoughts" could be the result of a bad day, bad week, bad month, or bad year. Based on the OP idk how long this has been happening for.
Maybe the guy has depression but has been in a rut for the last few months. Sure forcing a phychiatrist to tell him that is an option, but maybe a friend could over similar advice. If the OP's brother isn't close with him or maybe even his mom then hearing "go see a shrink" could just be something empty to him: a throwaway line from people who aren't really getting to the core of WHY he feels that way
But having the cops come take his gun and put him in time out may just make him feel like a shithead. I don't know the situation and I'm not pretending to be a professional, but it's doable.
I'm not telling the guy to literally say "yo get a hobby" but if OP started going backpacking with him, for example, that's a thing that could be fun/different/eye opening in regards to whatever is happening in his life that's causing his depression to worsen to considering suicide.
I just think there are real human interactions that can happen between "I feel suicidal" and "alright you're seeing a phych now" and those interations can be substantially more meaningful because, to him, it means the people around him actually give a shit about him as a thinking thing to sincerely try and help in a way beyond "oh no I hope he doesn't blast his brains out!" Like, caring that he's depressed at all to begin with would probably mean more to him
But also i don't have 10000% of the details and I'm absolutely not a trained professional. My experience was getting told "oh wow well if you're depressed you obviously need to go to therapy" without them actually trying to engage me at all themselves.
That resulted in me feeling like a problem and a burden that wasn't worth help from anyone outside someone who was paid to and I tried to kill myself. I didn't have access to a gun, but the gun itself wasn't the crux of the issue.
That was eight years ago and I've learned to cope and find meaning in my life myself. OP's brother could very well need professional help, or he just needs something meaningful and personal. I don't know and I don't pretend to: all I have is my own experience and I'm sincerely sorry if it comes across as asinine