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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,
Q: What size trigger pins does this lower use? The ones that came with my trigger were too small
Rainier Arms
01/04/24
A: This is designed for standard 0.154" pins
T
Tom_X
Verified Reviewer
06/11/22
Q: I just bought the receiver set, but it did not have any instructions and there is an inch long pin, in a plastic bag, zip-tied to the trigger guard... there is no spring with it, and it is not threaded, but one end looks similar to the safety-detent or take-down pin detent. Does anyone know what the pin is for?
Rainier Arms
06/13/22
A: That will be the extended bolt catch detent to allow the right side bolt release to function.
S
Steven H.
Verified Reviewer
11/26/20
Q: This receiver appears to have a threaded roll-pin bolt catch and an additional hole in the grip area for tension screw against the upper. Is this the case? There was no mention in the description.
Rainier Arms
11/27/20
A: This will uses a threaded bolt catch pin for ease of assembly, and has a tension screw.
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,
