Search:

Yes they did. The M1 Carbine was introduced into Vietnam by French troops during the late 1940s in their war with the communist Viet Minh forces. A large number of M1 carbines were captured and used...

Like these.... ?

1
Universal:
http://www.imfdb.org/images/7/72/M1_Carbine_Universal.jpg

2
Plainfield:
http://www.imfdb.org/images/a/aa/M1CarbinePlainfieldPM30.jpg

I don't know if the OP means a M1A1 or one of the post War commercials like this Plainfield??

http://www.m1carbinesinc.com/PMCVietnamApr%201966.jpg