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Our billet sets are CNC machined from solid billet 7075-T6 aluminum which is 70% stronger than the commonly used 6061 aluminum and finished with milspec hardcoat anodize to a surface hardness of 60 Rockwell. We have designed our lowers with an ambidextrous mag release and bolt release with extended latch for smoother deployment. The precision machining on our billets lowers will line up perfectly to our Rainier Arms UltraMatch Billet Upper Receiver or any other billet uppers out there.
Review by Jim B. on 23 Feb 2024review stating Best Lower Reciever I've used!!!
This lower is extremely high quality. I built a 300BLK SBR upper to use on my Daniel Defense Mk18. I built it with a DD upper receiver and rail as well as a Wilson Combat 11.3" barrel. I decided to build a lower to complete a 300BLK rifle and bought the Rainier Arms Ultramatch MOD 3 AR-15 Billet Ambi lower to anchor the build. I installed a BCM pa...Read MoreRead more about This lower is extremely high quality.
rts kit and buffer tube kit with a Magpul ACS-L stock. It went together seamlessly and looks fantastic! My only complaint is there were no notes or instructions explaining the pin that was zip tied to the upper. It is an extended pin for the bolt release for the ambi right side level button to function. Contacted Rainier via chat and had that answer pronto! Great customer service! Read LessRead less about This lower is extremely high quality.
Review by Sean D. on 15 Aug 2023review stating Quality lower
Great fit & finish. Hasn’t been to field trials yet, but if the fit and quality of the material are an indication. I am very optimistic about its performance.
Review by R B. on 10 Jan 2023review stating Best lower ever! IMO
I have several premium tier AR lowers, Radian, LMT, PWS, ADM, Knights Armament & and a few others. The fit and finish on this lower surpasses them all. The only other company that I have ever seen do this level of quality work is Mega Arms which is what the upper is that I mated the lower to. The fit is so well there is 0 wobble between the up...Read MoreRead more about I have several premium tier AR lowers,
per & lower & the finish is just beautiful! Have been waiting over a year to buy another. I highly recommend!! Read LessRead less about I have several premium tier AR lowers,
Review by Jim B. on 23 Feb 2024review stating Best Lower Reciever I've used!!!
This lower is extremely high quality. I built a 300BLK SBR upper to use on my Daniel Defense Mk18. I built it with a DD upper receiver and rail as well as a Wilson Combat 11.3" barrel. I decided to build a lower to complete a 300BLK rifle and bought the Rainier Arms Ultramatch MOD 3 AR-15 Billet Ambi lower to anchor the build. I installed a BCM pa...Read MoreRead more about This lower is extremely high quality.
rts kit and buffer tube kit with a Magpul ACS-L stock. It went together seamlessly and looks fantastic! My only complaint is there were no notes or instructions explaining the pin that was zip tied to the upper. It is an extended pin for the bolt release for the ambi right side level button to function. Contacted Rainier via chat and had that answer pronto! Great customer service! Read LessRead less about This lower is extremely high quality.
Review by Sean D. on 15 Aug 2023review stating Quality lower
Great fit & finish. Hasn’t been to field trials yet, but if the fit and quality of the material are an indication. I am very optimistic about its performance.
Review by R B. on 10 Jan 2023review stating Best lower ever! IMO
I have several premium tier AR lowers, Radian, LMT, PWS, ADM, Knights Armament & and a few others. The fit and finish on this lower surpasses them all. The only other company that I have ever seen do this level of quality work is Mega Arms which is what the upper is that I mated the lower to. The fit is so well there is 0 wobble between the up...Read MoreRead more about I have several premium tier AR lowers,
per & lower & the finish is just beautiful! Have been waiting over a year to buy another. I highly recommend!! Read LessRead less about I have several premium tier AR lowers,
