1964 dated Vietnam Era Olin Winchester M14 Rifle Ashtray

[LE LOUP DES MERS]

(Not sure if this is the right place to post this so feel free to move this if need be) Bought this ashtray and I have never seen one before. Not sure the history on it so wanted to get more info from you guys, did I find a rare item or is this common pieces? I tried looking it up and the only other collector that posted a photo of one was on the M14 forum, he claims it's rare and was givin out to military personnel during the Vietnam war. Not sure if I got burned or did good but I paid $56