What a great thread bringing back a lot of memories. While serving in an Air Police unit (68/69) I was issued a Model 15 along with my M16. But I brought with me a Model 60 and carried it everyday. Technically we weren't suppose to have personal weapons but a lot of us did, something that is probably unheard of today.
Speaking of Viet Nam, I went back in 2008 with a few other vets and we really enjoyed it. A lot of our former air bases are still in use, just like they are all over SE Asia. The people were very friendly and going back was a great experience.