There are different ways to adjust a 1911 trigger, but the easiest way is to use an Allen wrench.
Here’s how to do it right: Cock the hammer and insert a 1/16″ Allen wrench into the trigger’s set screw hole, which is near the bottom. You’ll notice that because of the trigger guard, you can only get about a quarter rotation on the screw per turn. While holding 1911 in a standard fashion with the grip safety ON, tighten the set screw (clockwise) as many turns as needed until releasing the trigger does not release the hammer.
Hold 1911 in a normal manner, gripping the grip safely. While holding rearward pressure on the trigger, start loosening (counter-clockwise) the set screw. The hammer will release at some point; when it does, continue to loosen the set screw another 1/4 turn for optimum performance.
On Colt Series 80 pistols, extra overtravel is required to raise the firing pin block enough to allow free movement of the firing pin. Once you set the adjustment, stake or Loctite the screw so it doesn’t back out.
Make sure you have the gun unloaded before you start adjusting anything, and remember to tighten the screws after you’re done. Be careful not to over-tighten them or you could strip the screw head. If that happens, you’ll need to find a replacement screw or take it to a gunsmith.
Happy shooting!