@Viech Yes, you could send me the texture, it would help!
@Janev Thanks for the suggestions, I modified the charging handle and the buttstock, and also changed the trigger a bit, but I'll work more on it when I start baking the low poly (and create the final high poly model).
@Stannum you remind me a lot of my college days (Product Design) when I had to present an idea to my teachers and they went on and on about correcting some things and modifying the design to fit some fixations they had with little relevance in the end or just out of my reach.
Thanks for the suggestions, I hope you also forwarded them to the artist to which the SMG concept belongs to. I don't feel right changing someone else's design when the requirement to stick close to it (unless for a really really good reason).
I increased the size of the switches and rounded the buttstock. I'll also widen the front grip.
Changing the recessed rails means changing a big part of the look of the gun. I don't think anyone will notice that today's attachments won't slide in. That pin position that interferes with the magazine is irrelevant (maybe it joins the extruded part from the front of the gun to the two grips and doesn't go all the way through). The curve that doesn't fit is part of the concept, and the buttstock is going to be also extendable, so its length is variable. I did change its width as much as I could.
Anyway, here are the changes to the high poly, the baked low poly is on it's way. The magazine will be done in the end, since it's a separate object.