The "less flat" ( more rounded) with a ever so slight angle to the top of the cylinder stop, the "thinner" the line...nature of the beast.
a said above, a bit of oil on it, when you are gonna shoot it, does lessen the 'wear' ....its when this 'line' is zig-zig, interupted, skips ,etc , . then there is a problem..........the line should be the same , the entire length, as there is no additional pressure on the 'stop' during the cycle, once it unlocks (jumps/releases) the spring keeps the pressure upward, and the nose of the trigger is angling down, and away from the face of the 'stop'.
Really 'neat' the thought that went into this design............

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dan
NRA Benefactor,PMA