Using this Udemy course found here: https://www.udemy.com/share/101zieB0EccllXRX4=/, I started to learn more around weapon design and creating high poly meshes and using retopology methods to create a normal map. A lot of the modelling sections of this course I did with the knowledge I had rather than use the course.
First of all I started by creating the high poly mesh using the Udemy course, After I started the retopology and finished it on my own, after joining all the objects in both the high poly and low poly model I scaled them down to be more life like, before using smart UV project to unwrap the low poly object. Then I created colour ID maps for the some what similar to the initial substance painter colour I wanted to use on the model, I download some of the textures from substance source and put them all together in substance painter. Finally I took the textures and using node wrangler added them to the low poly mesh in blender to create the final render.
The final high poly mesh had just over 1.8 million faces and after retopology the low poly mesh had 6500 faces.