Thank you for the Heads up! I remodeled my grip for better optimization. I don't know if there is a better way to approach this, but this is what i did. I have a plane inserted in the grip to avoid unnecessary polygons. if there is a better way, it would be much appreciated.
I see a lot of possible optimizations, also check your cage and fix those "Crown" Like borders in your cylinders, I see that you waste polygons in some unimportant parts and you lack them on some others, but you are not in the wrong path ;)
Inside the UV editor select all the uv's and go to Polygons>Merge UV's (click on the dialogue box option) then set the threshold very low .00001 and merge. If that doesn't work then the vertices aren't actually connected and you have to do the same thing but for the vertices.
Use the first one if you don't mind having many polygons in your models or if there won't be many of those soldiers during gameplay Since it has much better topology. Use the second one if you are trying to go for a more low poly approach.
Hey, about the problem displaying transparency. I had this same problem for a long time, and there is a setting that fixes it, or at least it did for me. Go to the shading drop-down in the viewport and make sure "Polygon Transparency Sorting" is checked. That should do the trick, I think.
Haven't see the game in action, but usually those are particles/billboards/sprites... polygons that always face the viewer. Doom 3 had a nice trick where they faded the transparency of the sprites as you got parallel with the emissive surface, so the glow fades away nicely.
Cody a.k.a warghoul wrote me one of the best scripts ever. It refreshes the textures on any selected models, nurbs polygons, .tga .psd, whatever. I use it every 5 min at work. Perhaps ask him if he can release it to the public?
If these are for third person, 2048 is way too big and even 1024 is a stretch. Your polygon counts are also very high for third person. The diffuse textures seem a bit too... textured. The Thompson receiver looks like stone, and the 1911 looks like marble.
Added more polygon to the edge of the shield giving it a much smoother look. I darkened the metal texture adding a few scratches to it and the wood texture also. As for the leather straps, I added by texture some studs and I also curved the shield a bit more.
If you are having so much trouble rendering the ambient occlusion map off the high polygon model, try just rendering it out off your normal map. It is not as accurate and complete, maybe you can use the combination to archive the best result possible.