the threads are the standard 6-48?? anyways talley sent me the 8-48's or whatever next step larger screw is, not a problem though as they sent out replacements. in any event if you want a lightweight ring just use the factory rings, they seem to really line up well I think its because tikka does such a good job of machining the rail on the top, the rest of the machining is top notch as well.

the plastic stuff did suck to remove, I would have gladly used the factories on this gun however they would not clear my OBJ and varmint barrel