This video demonstrates the correct [and cheap] way to perform a trigger job on an AR-15 with a standard “mil spec” semi-auto trigger. It will guide you through the “what and where” of properly stoning the fire control group [FCG] components with an armorers stone. It also provides a detailed how-to on swapping out the hammer / trigger / disconnector springs for a lighter set using the JP Enterprises Reduced Power Spring Kit [3.5#]. Please note, this kit can have issues with low-sensitivity primers. If you need to run those, you might try the 4# or 4.5# kits instead. Having said that, this 3.5# kit has worked flawlessly in our reliability tests on several variants of civilian .223 as well as the NATO stamped M193 and M855 variants of the 5.56mm.
This will give you a major improvement in trigger quality and significantly reduce the pull weight. Do not take a buffer wheel to the hammer or sear like some YouTube channels are suggesting… unless you specifically don’t like a clean breaking trigger. Most gunsmiths will generally agree that power tools have no place [or very little place] in the AR-15 FCG. Keep your edges sharp by using a proper armorers stone. This will give your trigger more of a “glass rod breaking” feel.