the ball 68 caused by normal upward biasing of the springs 54 56 produces a fine clicking adjustment with regards to elevation of the sight moreover the screw 34 is provided with a straight central channel in its head for accommodating a flat head screwdriver or similar tool for vertical adjustment of the sight however if desired the head could instead have a hexagonal opening for accommodating an allen wrench such as the opening shown in the screw headed stop pin 72 shown in fig1 moving again from right to left in fig5 the sight block 38 is integral with tongue 36 it includes a dovetail channel 74 for slidably and removably housing a sight leaf such as that shown at 18 the dovetail channel is of substantially circular shape and has at one side an elongated groove 76 for slidably receiving the stem 78 of a key shaped windage bar 80 attached to the back of sight blade 18 as best shown in fig4 and 5 the semicircular portion of dovetail channel 74 comprises a three step bore having a widened portion 82 at one end for receiving the head of a windage screw 84 a narrower central portion 86 for slidably housing a right cylinder portion 88 of key shaped windage bar 80 and an end portion 90 that is actually a hole in the side 92 of block 38 for receiving a pin end 94 of the windage screw 84 the hole 90 acts as a bushing and rotatably supports the windage screw in the.