I have owned a number of DPMS rifles. None of them worked well, Bad Chambers, a broken FSB, Broken stocks, Out of spec Top Rail. Not to mention the general lack of QC they have.
The lowers I have had were not as well "finished" as others. I am not talking about the Parker job. I mean the final machining was much rougher than on any RRA, Colt, S&W or even Bushmaster I have had. Lots of flash, etc. One stripped lower I purchased was so bad that it cut the web of my hand till I put a MIAD grip on it.