I've built a bunch of AR's and have used all manner of LPK's. There's not much difference that I can see between a Colt and a DPMS vs. RR or anyone else on dimensions and proper fit. There might be a difference on the finish of the parts.
Here's a near-mandatory tip: Get a set of REAL roll pin punches. Don't just use a pin punch intended for straight pins and try to nail the roll pins in with that. The end of a pin punch invariably slides off the roll pins and you bugger up the finish of the AR. Get a real roll pin punch set and do the job right - the finish will look much better when you've not nailed a punch into it.
Some optional, but useful tips:
1. When you're putting in the pin for the trigger guard, put the back side of the trigger guard on a block of wood or a rubber hockey puck, so that you don't blow off the back flange of the guard.
2. When you're putting in the roll pin for the bolt stop, put the pin in from the rear of the receiver and put a piece of masking tape on the side of the receiver to protect the finish. Be gentle and observant of the pin alignment so you don't break off the bolt stop "ears."
3. For the takedown pin detents, keep them in place with a slave pin (you can make this from a piece of drill rod) as you start the pin. Put the slave pin in from the left side of the receiver, then gently push down on the detents with a probe or small screwdriver, and push the slave pin far enough to capture th detent.
Put the takedown pin against the slave pin in the hole, then gently push through from right to left. Wha-la, no more flying detents.
4. Put the pistol grip on only partly tight before you have the safety installed. It's much easier to fiddle the safety into place with the detent under the grip a bit loose than to try to ram the safety lever into place against a full-push detent.
Lastly: Wear safety glasses when putting together guns with lots of springs and detent plungers that can go flying. There's no point in getting poked in the eye with a spring or detent.
