Shield 1.0 or 2.0?
I'm gonna guess 1.0 because the new ones have the over travel stop built in which is great becasue these guns have a ton of over travel.
so in the 1.0 shield to reduce the over travel, you have to close the loop on the trigger bar. mine had so much over travel that I actually shaved off a little bit of the tip of the loop so I could close it farther than the stock would allow.I also have an apex sear which breaks sooner than the stock so that increased the over travel slightly as well. after adjustment the trigger will have more pre-travel but a much better feeling break. over travel is the enemy of accuracy.
in regard to the reset, you can get the apex sear and sear spring and that seems to increase the tactile reset quite a bit on the shield. my reset is pretty fantastic compared to others. there is also one other slight adjustment that I've made to all my 1.0's that also increases the reset slightly but its really hard to explain. Basically I tweak the entire trigger bar loop a little bit inward (starboard ) so that when the bar is reset it pushes further away from the sear so when you release the trigger it has a slightly longer distance to smack the sear block...creating a stronger click... does that make ANY sense?