It could be much better. My two biggest problems with the set is your use of Horn Drill and Rock Wrecker. First of all Horn Drill has a 30% hit rate. That means you will be missing just about 2/3 times. You may argue Zoom Lens may answer that problem. But it doesn't as it only raises the accuracy by 10%. That doesn't mean its raising it to 40 base acc. It means its being raised to a grand total of 33 base acc. That's an amazing 3 extra base acc. Another reason I am not keen on your use of Horn Drill is the fact it is extremely nooby and reliant on luck therefore is banned in most competitive battles. Now we move on to Rock Wrecker which may have a nice 150 BP but it has a 1 turn recharge effectively making the BP 75 per turn. I suggest replacing it with a move like Stone Edge or Rock Blast.
Try this set
-Stone Edge (High Power stab)/Rock Blast (More reliable stab with ability to break Sashes)
-Earthquake (High power stab)
-Megahorn (Nice coverage)
-Ice Punch/Rock Polish (Good coverage or double speed)
As for the item I would use Choice Band which increases your attack by 50% bringing it to around 600 at LV 100. If you want a Rock Polish set then go Life Orb/Leftovers for extra damage or nice recovery.
Comment if you want evs, though I doubt you will.