This manhwa is from the author's larger universe where Dokgo, Tong, and Blood Rain happens, it seems like it's between Blood Rain 1 and 2 (all of these are awesome and you should read it). This one isn't too bad either, has a bit more of a "manhwa-esque" feel to it with the main character being a lot more edgy at times. I'm a sucker for the author so I'm biased but this is still much better than your avarague low-tier ORV style crap, with the other series being leagues above your mid-tier kortrash like Solo Leveling.
Not just that. There are so many times where the mc would've been absolutely fucked if any of his enemies had a gun, that I can only assume they don't exist in this world.
On Blood Rain there's a whole thing about the gun laws in korea and how they kinda have at least knowledge of most of the guns that have entered Korea, even the illegal ones, and they aren't very many. A local gang that preceeded Doo-Hyun had one or two in Tong and these chinese guys with Xiaomin and the old dude in the cabin have a few as well iirc.