The mod is currently broken, as you can see from the comments. Some users (such as Artyom) mentioned how to fix it, but weren't clear how to do it, so here's how.
It takes 10-20 minutes depending how much experience you have. It's probably easier to just get another mod, but this is the only one I know whose explosions can (somehow) kill the Combine helicopter, so I wanted to fix it instead.

Short version:
- Remove every line in the code that says sound.Add(soundData)

Long version:

1) Extract the mod. This is done by drag&dropping the mod's .GMA file (located at SteamLibrary\steamapps\common\GarrysMod\garrysmod\addons) into gmad.exe (located at SteamLibrary\steamapps\common\GarrysMod\bin). You'll recognize the .GMA file, it has the same name as this mod. This creates a folder with the same name as the mod, in the addons folder.

2) The newly-created folder has a bunch of text files. You must edit some, to delete all lines which say sound.Add(soundData). There are 17 such lines in the following locations:
- lua/weapons/cod4rm_fgm148javelin/shared.lua lines 313 and 323
- lua/weapons/cod4rm_fgm148javelin_c/shared.lua lines 313 and 323
- lua/weapons/cod4rm_fim92stinger/shared.lua lines 331 and 341
- lua/weapons/cod4rm_fim92stinger_c/shared.lua lines 331 and 341
- lua/weapons/mw2_fim92stinger/shared.lua line 318
- lua/weapons/mw3_fim92stinger/shared.lua:318 lines 318
- lua/entities/ent_cod4rm_javelinmissile/init.lua lines 14 and 23
- lua/entities/ent_cod4rm_javelinmissile_dir/init.lua lines 14 and 23
- lua/entities/ent_cod4rm_rpgrocket/init.lua line 15
- lua/entities/ent_cod4rm_stingermissile/init.lua line 14
- lua/entities/ent_stingermissile/init.lua line 14

3) Looks like Garry's Mod prefers to open the mod's GMA file instead of the folder we created during Step 1. The fix isn't in the GMA, only in the folder. The only fix I know is to uninstall/unsubscribe the mod. Make sure the GMA file is gone, only the folder we created must remain. The game will still see the mod because of the folder. Restart the game and everything should work fine.


Notes: The Claymores are still weird, but they were bugged before the mod broke, so that's nothing new. Also, I don't know what exactly the sound stuff we deleted was meant to do, because as far as I can tell, all the sounds that used to play still play without issue.

If you tried this and it didn't fix the issue, feel free to ask. But remember: the console in-game prints the errors, so it will tell you exactly what went wrong, such as probably forgetting to delete 1 of the 17 lines mentioned earlier.