The RRA kits are very good.
You will get a lot of different opinions as folks have different preferences.
With a few exceptions lower brands, upper brands, doesn't matter. The internals are more important than anything else.
I have both and they are both awesome. I also used Del-ton and nothing but good experiences. Delton and RRA are cut in the same mill as colts and their uppers and carriers are coming out pretty well squared.
These are a few simple things that you need to look for to make sure your carbine is up to spec:
- Bolt Carrier Group with a properly stacked key.
- shrouded firing pin.
- Nice strong extractor and extractor spring.
- Magnetic particle tested.
- Good and crisp trigger parts set - RRA will provide a very nice 2 state one for the same cost of the single state. Very good performance for the money if 2 stage is what you want.
- After that the typical, with a good barrel, make sure they are properly head spaced, gas block/sights squared and that's pretty much it.
If you buy a set with a built upper normally those brands are trouble free but I run them top to bottom anyway. Whether you get one or the others see if you can get a matched billet. I have some matched dead on and some are not but they work just fine with the wedges.
In case you want to consider, the best billet (tightest) I have is the SI defense with the flared mag and built trigger guard.
Also the sun-devil lowers come out pretty nice.
It is hard to go wrong with any choices. Just make sure to check things to make sure they are up to spec.
Picture of Rock River Arms Kit with M4 barrel (not chromed for accuracy) and the Adams piston. I have 4 of these with piston and work great. The 2 stage trigger is awesome...
That one is a Delton upper with American Tactical Lower....
That is a national Match HP barrel from RRA (wylde chamber) with a RRA lower and the 2stage trigger. This rifle is producing .5 MOA and better consistently with handloads....
Whether I use the Adams piston or the original system, the carbine is for close range tactical drills or long range accuracy they all are top
performers. I can look for more pictures of other systems if you want to see pictures. But this forum is full of other posts with endless counts of great builds and great combinations.
Cheers,
E.