I had a problem with the aftermarket triggers on my ar15. I use my lower on my .223 upper and 6.8 upper. The SSA ammo uses a harder primer and the lighter triggers would not strike the primer hard enought to fire the round on each try. I put a lightened spring kit in my lower with the standard hammer spring. No problems at all with hundreds of round fired. It is aroun 3.75-4.0 trigger.
I would just look at a spring kit. They are a lot cheaper and do a good job at lowereing the triggers weight.
As a note: I do not like two stage triggers on rifles. Single stage only for me.
When I did have a two stage, I could not shoot it accuratly. I traded the RRA two stage for a single stage. I just ate the cost.