I just put a Jard single-stage adjustable in my 15-22. The trigger comes with a new hammer spring; you don't need any other springs. Installation and adjustment took about 45 minutes and is pretty straight forward. You can d/l the instructions from the Jard web site before purchasing.
One of the adjustments is the sear engagement depth and this adjustment has a direct effect upon the trigger pull weight. Using the 1.5 lb trigger spring I could get the TP down to 1.75 lbs as measured with a Lyman digital TP gauge but I was just not comfortable with how it felt - it felt a little unstable, for lack of a better word. I increased the engagement to what I was comfortable with and wound up with a 2 lb, 5 oz pull with just a hint of creep. I am satisfied with that.
One thing to be aware of; the sear engagement screw is a 1/4"x28x1/2" hex screw that goes into the same hole the the pistol grip bolt does and is screwed up into the FCG cavity. The original pistol grip bolt is now too long and can bottom out against the adjustment screw if one isn't careful. The trigger kit includes a replacement screw, but it is made for ARs and is a tad too short for the 15-22. You will need a1/4"x28x3/4" hex bolt - about 50 cents at your local hardware store. One further note; the boss that the grip bolt and adjustment screw screws into is polymer. Be careful not to cross thread either one. It is easy to do.
The whole process isn't difficult; just pay attention to what you are doing. I almost had a hard time justifying $150 for a replacement trigger, but no matter what I did, I couldn't get the factory trigger below a creepy 4.5 pounds. Now I'm glad I spent the money.
