It is a DPMS - I mistakenly use the AR-10 as a generic but I now am aware AR-10 is specifically an Armalite. I was under the impression the the BCG's were totally interchangeable as long as you didn't try to put an Armalite bolt into a DPMS carrier or vice versa. Makes perfect sense re the barrel extension though. Obviously still some to learn on this platform. Rainier is on my short list of suppliers. I've only dealt with them on a couple of occasions but they always get the job done at a good price with a good selection. I'm still hunting up parts here and there - sights and a couple of specific tools for the .308, buffer extension tube, etc. WHereas I've done a couple dozen AR-15 builds, I will only do one or two .308's. Maybe a 6.8 is in the future. Thanks again for your help. Good advice is hard to find . . . that's why I've been married for the better part of 40 years. I only need 3 words - YES, NO and MAAM !