Like?
Anything that's not a normal, irl gun. We have so many as it is.
At least one crappy gun pack is made every month and they are all the same. Trying to copy Battlefield or CoD with it's realistic gun fire, muzzle flare, and projectile damage.
What comes out of this is always the same: A pack of guns that use a crappy ammo mod, that isn't well damage balanced, named after real gun in suffixes, that looks like it was taken from your average shooter game running on an N64 port.
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If your gonna make guns,
1) don't name your guns after the 'in real life' counterpart. I don't know what the difference between an M4A1 and AK47 is, but I can tell you the difference isn't important enough to include. Just call it a "Machine Gun" and be done with it. Nobody's gonna mistake what it does.
2) Don't model your guns completely off realistic guns. Make your own stuff up, its more interesting that way. Make your shotguns shoot fire, give your pistols bayonets, do something different. I'm willing to bet we already have at least one of every gun type possible.
3) Include emitters to your projectiles. I'm sick of the "no emitter trail" projectiles that most "mainstream" gun packs have. I can't see where my bullet is going without one and it looks overall tacky. Doesn't matter if that's no how it is in real life, this is Blockland.
4) Balance damage on your weapons. Nobody wants one or a few guns in a pack that do more damage faster than the others. They usually end up in the server hosts hands just to be better than you in a DM anyways. That doesn't mean that all the weapons have to do the same amount of damage, it just means that there shouldn't be one gun that Annoying Oranges the rest. Remember, you have projectile damage, a radius damage is you wish, and reload time as factors. A gun that does a lot of damage, should fire slowly.
5) Do not include projectile arcing. It's really annoying trying to aim at somebody just to have your sniper shot fall short as you threw it. Seriously, bullets only arc after a very long time. Who came up with this in the first place??
6) Ammo. If you want your guns to have ammo, please include auto reload when your out of bullets. I can't stand guns where your firing at an enemy and you start dry firing. I don't have time to reload, your best bet at that point is to throw it away and use your alt gun.
Better yet, do away with ammo entirely. Saves you and me a headache...
7) And add headshot support. It's always a good idea to add headshot support..
All this being said, see anything that GCat makes as a template of "a bad weapon pack". That guy makes nothing but garbage.