Well, I think I can kinda tell why your CAR didn't work... from your original code, you only check to see if the gun being used is the M9.
I think what you want is something like (again, not sqs-savvy)
? _gun in _NonStanWeapons: goto "Unarm"
Basically, check to see if the gun being used is non-standard.
Edit:
Maybe test it by:
? _gun == "LSR_car15_sd": goto "Unarm"
Not sure of the quotes in the conditional.
Edit2:
Looked again at Planck's stuff. Use his parens for the code.
Also, do away with the conditional completely, maybe. You really don't care WHAT they are firing, you just want to make sure it isn't one of the nonstandards.