So I have a couple of Sig 556's/551a1 from the good ole USA. I have a Sig550 from JDI that I am interested in making 922 compliant. I checked the SIG 556 trigger and its pull weighs in at a lovely 4.5 pounds of pressure. The Sig 550 comes in at just a bit over 8 pounds of trigger pull which I hate.

I installed the shootsight trigger components in the SIG USA gun and the new components and spring bring the pull weight back up to just over 8 pounds of break pressure.

I purchased the Shootsight 556 trigger for the 922 parts and after playing with the trigger kit I'm a little confused by the Trigger plunger behind the trigger and what it really does? Is the purpose of the plunger to provide resistance as a drop safety?

Has anyone used the shootsight 556 trigger?

The Shootsight 556 trigger comes with a booster spring and that fits around the other trigger resistance spring inside the trigger. I am curious if when I put this together if it is a must install or can I just the sig SIG USA Trigger spring to lessen the trigger pull?

Obviously I am not a gun smith but I do like to tinker. I can live with 8 pounds of pull but really like my SIG USA 4.5 trigger pull better. Just trying to figure out what is safe and what I can do to ease the trigger pull on my 550. Should I just swap the SIG USA parts with the SIG 550?

The second spring is required per Art. Some good info on the plunger here

In my experience, merely adjusting the plunger rearward until the trigger barely stops against it before it breaks will give you a great trigger in a US or Swiss gun.

quote:

Originally posted by KSGM:
In my experience, merely adjusting the plunger rearward until the trigger barely stops against it before it breaks will give you a great trigger in a US or Swiss gun.

Yep, that is what I'm finding too. Backing the plunger off to just behind the break has the pull weight to about 4.5 pounds.

I avoid adjusting the plunger to behind the break, because you lose the reference point of the "wall" it provides. I bounce between ARs and Sigs, so I don't want the Sigs to have a "rollover" break. If you're a big AK dude, it probably won't bother you so much.

This message has been edited. Last edited by: KSGM,

quote:

Originally posted by KSGM:
I avoid adjusting the plunger to behind the break, because you lose the reference point of the "wall" it provides. I bounce between ARs and Sigs, so I don't want to Sigs to have a "rollover" break. If you're a big AK dude, it probably won't bother you so much.

Yep, it bothered me. I moved the all the plungers up for that better feeling and resistance at the "Wall". Most are breaking at around 5.5 lbs of pressure after being readjusted. I can live with that.