Hi guys I present you some GTA IV tutorials by Metalwarz from which I learned from on how to convert weapons. He is a popular GTA 4 modder.
Convert Player Model To Ped Model
Convert Ped Model To Player Model
He also release lots of his mod on his channel:
> https://www.youtube.com/channel/UCWwXqD7VAP8MsPLrG-pDAqQSuch as: