I don't think they are Nato grenade launchers, maybe made to launch grenades at Nato troops, but not Nato launchers. Yugoslavia is a former Eastern bloc country which has was an enemy of NATO going back to the end o WWII.

If you want a cheap deer gun why not buy a Mauser or Mosin? You can get a nice Yugo M-48 or a Mosin M-44 for around $100. You will need to reload for the Mauser to get good accuracy in hunting ammo but you would probably have to do the same if you got an SKS anyway. The 8x57 and 7.62x54R cartridges are far more powerful than the 7.62x39 popgun cartridge. The rifles are lightweight and accurate as well.

Alcohol, Tobacco, and Firearms... who's bringing the chips?