I have with no success been looking for an affordable trigger to replace the stock trigger on my COLT HBAR.  In previous conversations with RRA, I was told that no RRA NM large pin triggers would be available.  Just a moment ago on their website I saw the following item:

AR0093NMKS RRA NM Two Stage Trigger Kit, for large pin lower
               Will fit large pin lower with block.

As my HBAR is a post ban COLT product, it has I would think the large pin lower.  However I have no idea what a "block" means.  What is a "block?"  How does one determine if a COLT lower receiver has a "block."  Am I correct in thinking that this RRA NM trigger will fit my rifle?  Any information will be much appreciated.  Sincerely.  Bruce.

I know this wont be the answer you are looking for but for around 40 dollars you could send your trigger out for work and get a 3 or 4 pound pull and not waste money on a new trigger.
www.triggerwork.net     guys name is bill and there is a huge thread here full of praise on his work.i will be sending one here in a few days.sorry if you are not interested but some people dont know this is a great option.send him an email.

ETA,just saw you are from ga,make a visit by the georgia home town forum.great guys there and lots of info on upcoming shoots.

here is a quick crappy cell phone pic of a colt with the block with an rra nm trigger.
so wheather you have one on your gun or not the trigger will work.

Hope it works out for ya.  RRA NM 2 stage is a great FCG.  I'm loving' mine--we're still on the "honeymoon"!  Made a world o' difference in my AR.

That's the only thing that kinda sucks on Colt lowers......

RRA is a good choice or getting your stock setup work will be 1/2 the cost with great results.

Bill

if you are set on getting the RRA, get it tuned by WOA or send it to Bill Springfield (i think that's his name) he has gotten really good reviews on this forum for trigger work...