Texas thanks for that post, a lot of good information there about different triggers!
The trigger on my National Match M1A is one that has given me a "what the heck" moment once. If when shooting off a bench rest or sand bags, and holding the rifle somewhat loosely, it has "double fired" on me.
I now really pull the M1A in to my shoulder nice and snug when on the bench, and it does fine. Held a little loose, I believe the rifle kind of "bump-fires" due to movement and recoil.
I saw this happen once to a friend firing a service grade M1 Garand while laying on the ground resting the rifle on a sand bag, two fast shots that sounded like one shot. He looked up and said "What the "