nice! keep at it. Your cobbles seem a bit melty/smooth, maybe the specularity map needs adjustment, I'm not sure. IMO rocks are really much more difficult to make than they seem; eons of geological history is required to make each rock. If you search for cobble there's a few good examples you can look at…
Comming soon: helmet and add-ons. Two of his guns, I'm supposed to make it 'upgradeable', or 'modular', so there's the base gun, and the top changes to other things.
Screenies from latest freelance project that I've rounded off; Meridian Line. Highly modular geometry and textures designed to procedurally snap together.