I'm in the process of "building" a 9mm setup, and will be changing out the notched hammer for a DPMS hammer.

How easy is this?  I read the "Build it yourself" section, but it doesn't really help me (or maybe I'm too stupid).

I don't actually have the hammer yet, but am looking to find out how to do it exactly.

ETA:  I've never installed an LPK or taken my trigger guts out before.

Pretty simple, actually.

-Drive the pin out and lift out the hammer.
-Pay attention to the orientation of the spring.
-swap the spring over to the new hammer, just like it was on the old one.
-put the new hammer in with the sping legs in the groves in the trigger/trigger pin.
( I use a slightly smaller punch pushe through the receiver, and hammer to help align all the holes while I push the retaining pin back into the receiver.)

This is so easy that yes, it does look "too easy."  But it isn't.  Simply push out the hammer pin, remove old hammer and spring, put spring on new hammer, push the new hammer/spring into position, and push the pin back in.

I asked this same question (for the same reason) about 6-8 months ago, and got good and supportive advice (and a few jibes).  It really is just about the simplest thing you can do to an AR lower.

Quoted: I'm in the process of "building" a 9mm setup, and will be changing out the notched hammer for a DPMS hammer. How easy is this?  I read the "Build it yourself" section, but it doesn't really help me (or maybe I'm too stupid). I don't actually have the hammer yet, but am looking to find out how to do it exactly. ETA:  I've never installed an LPK or taken my trigger guts out before.

Click --> "HERE"

In reality, it will take maybe 10x longer to load and locate the page than the 30 seconds it will take you to swap the hammer...  

Awesome, thanks for the info fellas.

I'll refer back to this thread when I actually get the hammer.  Then, after I put it in, I'm sure I will have one of those "Damn, that was easier than I thought" moments.

The description is to "drive" the hammer pin out and back in . This is correct but the reality is you only just tap on the punch with a light hammer . The pin is just held in place by a bit of spring tension in a tiny grove and that is all you need to overcome.

It is quite simple after you do it once

Update:

So I was bored, and decided to finally swap the hammer I got the other day.........and I was right, I did have one of those "Damn, that was easier than I though it was gonna be" moments.  Although trying to keep pressure on the hammer and spring, while lining it up with the hole, and getting the roll pin started was a bit of a pain.

I realized I don't have any punches of any kind, so I got creative and used a plastic chopstick.  It worked amazingly well, and obviously won't mar anything up, being that it's plastic.  If I ever decide to build up a stripped lower, I know what I'm using in place of a punch.

Anyway, onto my last question about this:

The hammer is in, and I dry fired it to make sure everything is working properly.  It dry fires fine, but I noticed the hammer pin isn't flush with the receiver like it was before the swap.  The pin has that groove directly in the middle, and another toward the end.  Does the end with the groove need to be on a specific side?  I'm assuming so, but would like a definite answer.

Since the hammer and trigger pins are identical, you could use either in either place.  The HAMMER pin is retained by the "J spring" inside the hammer itself, while the TRIGGER pin is retained by one or the other tail of the hammer spring.  The end with the groove doesn't matter in either case.  However, if your hammer spring isn't flush or nearly so on both sides, have you tried nudging it a bit so that it goes flush?  There could be a tiny ridge next to the central groove that's keeping the J spring from seating in the groove.