I'm no coder, but I am pretty sure that all you have to do is copy the weapon that you are wanting from the other mod's addons, and paste it into your current addon folder. I may be wrong, I may not be. I just wanted to make a quick reply, so your post goes untouched.
Born to Fight, Trained to Kill, Ready to Die,
But never will!
DayZRP Name: James "Delta" H.
DayZRP Orginization: SKA, FreeMedic's, S-Gru
DayZRP Friends: Lewis, Pandi, Juggs, Drinvkia, Charles, Alex