DPMS has also been making rifles longer than RRA
DPMS Firearms, LLC, founded over 20 years ago by President Randy Luth, began as a small government contract consulting company. Luth, himself a product of a precision machine shop that manufactured M-16, M-14 and M203 parts for Army contracts, advised other small machine shops how to find pertinent government contracts, develop the necessary quality control programs and complete the contract in a timely and profitable manner, all the while continuing to broker M-16/AR-15 Mil Spec parts to the commercial markets. After four years, Luth began phasing out the consulting portion of the business to focus primarily on the sale of .45/1911 & AR-15 parts, kits and accessories. During this time DPMS Firearms, LLC began designing and manufacturing rifle accessories and purchased a manufacturer of lower receivers, and with the ability to machine its own precision barrels, the DPMS line of AR-15/M-16 rifles was born.
RRA
The Larson brothers severed their connection with Eagle Arms in 1997 when that firm moved to Geneseo, Illinois. At the same time, Rock River Arms began to build AR-15 style rifles.
I must admit that the Larson brothers do have a good credentials one of them having been partners in Les Baer and the other at the Springfield Armory and I never said they built a bad gun just that I liked my DPMS