Are you tired of that gritty hard to pull Mil-Spec trigger on your stock AR15? Are you not quite ready to drop $150+ on a drop in trigger? Well there is a solution, and with some basic materials and 10 to 15 minutes you can polish your own trigger. This will in no way make your Mil-Spec trigger perform like a drop in trigger, but it will enhance it.
First lets discuss the differences between the two styles of triggers.
The Mil-Spec trigger is designed to function, period. It has a lot of tolerance built into the design to make it function no matter what. This is why they are gritty, heavy and have a mile of travel before the sear point is reached. This is also why there is lot of movement of the trigger even under the safe designation on the safety selector.
The drop in trigger is designed to function optimally. With a very low weight of pull, imperceptible creep of trigger and crisp “break” of the sear point. This helps with shot anticipation, slapping of the trigger and pulling the gun off target. All that being said it is designed to help you be more accurate with your shot placement.
The sear height on a Mil-Spec trigger is upwards of .060 of an inch or 1/16th of an inch. The sear height on a typical drop in is about .030 of an inch or 1/32nd of an inch. This is why you have a long travel on a Mil-Spec trigger and a fair amount of trigger travel under the safe condition without the gun going off. It is also why you have imperceptible travel on a drop in trigger, and must have little to no movement under the safe condition as well. The short sear height gives you a light trigger pull almost zero creep of the trigger, but allows for little room for error in the safety tang height.
Now for actual work.
You can watch my video here to see how I polish a Mil-Spec hammer and trigger. The first thing you will need is some fine sandpaper 400 grit will do fine. Then get a little light oil and a diamond stone or file. You can buy diamond files or stones off Amazon for under $20.
Trigger: Start by sanding the in the longitudinal direction ( the direction of travel of the hammer ) on both top and front faces. Use a flat surface and hold the faces as square as possible. You only want to remove the stock grind marks and smooth surface out. Then work both surfaces the same with a fine diamond grit file or stone. This will create an almost razor sharp edge of the sear point. Take the file or stone and LIGHTLY rub it along the knife edge a couple times just to break the dead sharp corner. The faces should start to look shiny and almost reflective. Be sure to watch the video as this process explains much better visually than in written form. Repeat the process of the diamond file or stone on the hammer sear point. Reassemble your trigger and oil it well with your favorite gun lube.
You should see a noticeable difference in poundage, length of creep and smoothness of travel.
As always be safe, shoot straight, and have fun.