M16/M4 trigger spring

[Irishjeeper]

I received a number of free springs from a friend as they know I build. These are labeled a burst spring. Can anyone enlighten me why the spring has different diameters, and one arm is at an angle. They don't look like a tradional spring I've used before. Any help is appreciated.70044

[markm]

I think the "ratchet"/"burst gear"/whatever it's name is... goes in the larger loop. I would imagine that the springs are worthless without that part because it'd flap around in the lower. I'm guessing at this because I don't have a burst lower to look at. Probably could google an image of it though.

[mpddoug162]

Fire control parts for a 3 rd burst are different than a semi or fa weapon. There is a ratchet gear in the burst control parts that one loop of the spring needs to fit over and it has a larger diameter hence the one side with a bigger loop.

[lysander]

While the loop on the right side is larger, and the leg angles are different, the A2 hammer spring will work in an A1/semi-auto, provided you keep the retaining groove of the trigger pin on the left side.

[lysander]

Oh, and by the way, the title of the thread is wrong the springs in question are hammer springs.