There’s a couple of potential problems with this I’ll outline.
Skimming the Surface:
Being able to adjust a small handful of stats for specific weapon types.
There’s a number of ways you can define the categories.
I’d go with something along the lines of: Automatics, Rifles, Snipers, Explosives, Shotguns, Melee Weapons.
The only adjustable stats would be: RoF, Damage, Ammo Count
I think this would be adequate for most purposes, and is fairly simple to explain to someone who is picking up your gametype for the first time.
I got the idea of weapon categories from the first two Halo games, where you could make it so only specific types of weapons spawn on the map.
Dangerous Waters:
Being able to adjust the stats of every single specific weapon.
The stats you can adjust are the same as above.
If a single gun is overpowered, it could easily just be removed off the map with forge.
Since a ton of specific weapons could be altered, the host of the custom games lobby would have to explain them all. These gametypes would likely be left out of matchmaking completely because there’s no effective way to explain all the intricate differences between them all.
You also have to make sure the menu doesn’t become extremely complex because of unnecessary options.
Crushed at Deep Sea
Being able to adjust the stats of every single weapon.
Being able to adjust the stats in-depth: RoF, Damage, Bloom Rate, Max Spread, Min Spread, Ammo, Headshot Modifier %
No one is going to use all of these options, and severely amplifies all the problems listed above.