If it is the small screws that hold the sight rail on they are 6-48 a very fine thread. I do have a couple of spares when I bought my 10/22 I had a look at the rugger supplied rail it was quite honestly crap so I bought a weaver rail that came with the screws and I still have a couple of the screws. If it is those screws it might be cheaper to by a 10/22 sight rail I can't see a company Having two different types of sight rail screws and it is probably cheaper than the postage form ordering the part from the Internet.