really nice work there very good detail.... if i may suggest: assemble the rifle in poser and texture it the way you want it- then export it as a .3ds file {make sure you check export object groups} some files are up to 90% smaller than the origional .obj file, when you re-import it just make sure nothing is checked except make normals consistant... it will come back into poser with the same size, position and textures as it had before export {personally i dont think 1.3mb is too unreasonable for such a fine model}

Y'all have a great day.