I have a colt A2 20" er and an RRA lower with a custom upper.  I tried switching my RRA 2 stage NM trigger into my colt lower and this thing wouldn't allow it.  I think I've heard them called sear blocks or something like that.  Here it is:



Sorry about the pic but you see that big thing in the middle with colt stamped on top of it.  That thing is in the way.  Does it come out?  If not, do they make 2 stage triggers that fit in there?  What in the heck is that thing?

I do have to say, I had both triggers out and found it to be a relatively easy job to take out and put back in.  The RRA 2 stage trigger was the easier of the the two because the sear is already connected, where the colt single stage has two different pieces that you need to line up.  Well, at least I learned something.

How to remove a COLT sear block

Thanks man.  Maybe I'll have to spring for a membership so I can view it.  Is it hard to do and does it require special tools?

Membership does have its advantages...

Even with the sear block removed the chances are that the trigger will NOT fit anyway. Your RR lower is a small pin lower and more than likely your Colt lower is a large pin. So, even if you take out the block the pins will be too small and the trigger will not work. Measure the pins on the Colt to see for sure.

That being said, unless you are pretty good with tools and know exactly what you are doing, removing those sear blocks can be a PITA. If you are not careful you can damage your lower.

Removing the sear block is simple and unless your a complete idiot, you can not damage the receiver using the method described in the link I had posted... If the pins from the colt fit into the RRA lowers pin hole, your OK, the triggers are transferable...

The pins are the same size.  Identical.  It would've worked if it twerent for that dojiggy in the way.  Oh well.  My colt is a sporter target model.  It's not ancient.  I really like it, but it would be a heck of a lot better with a 2 stage trigger in it.