I friend of mine recently sheared the bolt off of his MATECH Back Up Iron Sight which is actually quite common. Rather than bother with another flimsy screw and bracket, I pointed him to the BAD-BSM from Battle Arms Development. You know them for their selectors, but they also make a much improved screw and bracket for the MATECH.
The components of the BAD-BSM are thicker and stronger than the parts they replace. The parts are machined from bar stock and are designed to be less likely to be over-torqued.
Check out the BAD-BSM on BattleArmsDevelopment.com.