I had a DPMS AP4 308 and a Armalite AR 10 Carbine. I still have the AR 10A4. Since I no longer have the DPMS I won't commit about it. I love my AR 10! I've shot 710 rounds through it and never had a failure of any kind. I've only shot it out to 200 yards so far and it shoots way better than I do. I am no expert shot but I can hit a five inch target consistently at 200 yards and thats without straping the gun down to a support. Thats great for me. The 200 yard shooting is with a 3-9X40 Bushnell Banner scope. I can do the same thing at 100 yards with BUIS, I haven't tried them at 200 yet. This Armalite is a great gun and I would reccomend it to anyone.
Thanks aqain techmike for the valuaable info. I didn't think there was much to caring for the lower but it seems to me that you are the man to check with. I shot my Colt today and now have 2040 rounds through it so tomorrow theres a good chance I'll try out your extened cleaning method.