I think the best way to handle this is just to tweak the slot values in the json files on a case by case basis for weapons that seem overloaded. I think most of them are actually ok as-is; most weapons only allow one mod in any particular slot anyway, so even if a gun has a lot of mods, they’re not being placed un-realistically. Mods are also already restricted in what types of guns they’re compatible with. Even though a pistol has an underbarrel slot, it can’t use a M203 grenade launcher, only an underbarrel laser sight.
Also, a lot of the mods are for things that replace pieces of the original gun, like conversion kits or replacement stocks. We should actually think about adding some flags for mods that don’t actually add their weight or volume to guns they’re attached to (since they replace original pieces of the gun, which get removed). This would also let us add mods like collapsing stocks, that reduce a gun’s volume.
As for the original topic, I like the idea of just having a +x addition to the name in the hud. It’s small, it’s informative, and it’s cool in an old D&D sort of way.