Has anyone used any of the available drop in trigger groups that will reduce your trigger weight? If so, did it make a significant difference, and how hard is it to do yourself?

Tvone

I replaced my Bushmaster CMP trigger (which sucked) with a 2 stage Jewell. The Jewell is pretty easy to install and you can adjust the first stage weight, second stage letoff weight, sear engagement and overtravel. Go here for install instructions:

http://www.highpowerrifle.com/Jewell.htm

The Jewell breaks crisp like a glass rod and can be adjusted down to around 2 pounds . The cheapest place that I found to purchase a Jewell is www.georgiaprecision.com. They have the Jewell for $174. They also have the Rock River match trigger for $99. I don't have any experience witht the RR trigger but have seen some good reviews on them.

I just installed the RRA NM trigger in my Olympic yesterday. This trigger really is as nice as everyone says. It just dropped right in my rifle without any hassle. IMO, it's a hell of an improvement for $99...nice and smooth from the first-stage to the second with a clean break. Good luck.

*EDIT*
I'd never had the trigger group disassembled before this. Also, I have to admit that I wasn't looking forward to it, either. However, I've had quite a few other firearms disassembled before, and just by looking, it didn't appear to be difficult at all. The replacement trigger group is already put together (not loose parts needing assembly). RRA really did a nice job with this trigger, it's very simple and straight forward.

Installed the JP fire control pkg. in my Oly SUM. It dropped pull from 4.5lbs to just below 3lbs, cut my groups in half and eliminated that annoying two stage "creep" that I wasn't used to. Installation was straighforward, they include a video CD that shows you how to take out the old and install the new. Good product.
Don't forget to replace that pistol grip also.

Get your RRA NM trigger from ADCO. They sponsor this site. $98.44 shipped, haven't seen a better price anywhere. Steve is great to work with and he doesn't screw us on shipping ($4.00 anywhere in US). ADCO deserves our support.

Shabo

I installed a JARD single stage in my Bushmaster. I'm happy with it. It has lots of adjustment screws though, and may have reliabilty issues because of that. Different pull weights are available, mine being no more than two pounds. Now those tomato cans have no chance at all.

I have the JP triggers in two of my AR-15's and the Accuracy Speaks (Derrick Martin) trigger in a Stoner SR-25. I'm very pleased with all of them. Both require a little time commitment to install but, both come with clear instructions and, based on my own experience, both manufacturers are more than willing to help you out over the phone.

Jut did my second RRA in another of my AR's. Fantastic. Takes very little time for a great trigger and under $100.