Diopter; You may Not be aware of this, but there is a right way. AND a wrong way of assembling your L1A1s! The Central Hinge pin & screw have been assembled incorrectly on your rifles. The Slotted screw head should be on the LEFT side of the Rifle when pointing muzzle towards target. As Armourers, this was an Imediate indication that the 'User' when the Rifle was in Service. Had Illegally stripped the Weapon for cleaning above what he was allowed to do! The reason that an average untrained squaddie was not allowed to strip a Rifle further that the user handbook stated was. It was possible to lose some componants or incorrectly assemble that & cause possible subsequent damage! Also, SOME Soldiers used to 'Tamper' with the internals so the weapon went full auto! Im NOT telling you how, as you just MIGHT be tempted to imitate that practice!..Ha,Ha! Incorrect assembly from the wrong side will NOT affect the handling or function of your Rifles Diopter, so dont worry about that! BUT, Asthetically, & issue from factory. The screws SHOULD be inserted as I discribed previously. I know it's all stamp collector, or Rivit counter stuff, BUT. ther IS a right way & a wrong way. And a LOT of collectors would want things to be RIGHT! I hope this small snippet will be of some use to yourself & possibly other members? PETER, Im suprised you didnt pick this one up! Get down & give me 10 Pressups!!!!............