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Rifle Parts

Whether you're building a new rifle from scratch or looking to upgrade an existing firearm, our vast selection of rifle parts has everything you are going to need in that journey. At Rainier Arms' selection of rifle parts, you can find a wide variety of products including lower and upper parts, trigger parts, muzzle devices, and many more.

Explore our selection of high-quality parts coming from various leading manufacturers like Strike Industries, Magpul, BCM, and many more.

Also, don't forget to check our specially-made Rainier Arms barrels for your firearms.

Rainier Arms RUC DI 5.56 NATO Partial Upper Receiver

$400.00 - $480.00
Starting at 0% APR or $73.83/mo with . Learn More

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Rainier Arms RUC PRO MK1 5.56 NATO Partial Upper Receiver
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Verified Reviewer

0.0 star rating

07/31/25

Review by Anonymous User

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07/31/25

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Stanley M.
Verified Buyer

4.0 star rating

07/30/25

Good but still get a little blowback

Review by Stanley M. on 30 Jul 2025 review stating Good but still get a little blowback
At first install, I was going to return it because it would get stuck in the closed position but after cleaning my rifle and the new handle and lubing it, it worked itself in and works great now. My only other slight complaint is that the hole that is supposed to direct the gas away from your face actually allows a little puff of gas to rise up in your face when you are finished shooting. I think it would be better without the hole in the side of the handle. Overall I’m satisfied but since I am new to this, I’m surprised at how expensive a small part can be. Very well made though.

On Griffin Armament SNACH Gen 2 AR-15 Charging Handle - Black

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07/30/25

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Jordon P.
Verified Buyer

5.0 star rating

07/30/25

Solid and affordable

Review by Jordon P. on 30 Jul 2025 review stating Solid and affordable
Lightweight, sturdy, couldn’t argue with that price point at all.

On Rainier Arms AR-15 Urban Combat M-Lok Handguard

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07/30/25

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RICHARD B.
Verified Buyer

3.0 star rating

07/30/25

Fitment was not great on my gun.

Review by RICHARD B. on 30 Jul 2025 review stating Fitment was not great on my gun.
The fitment wasn't the greatest the grip did not fit tight to gun even when bolt was completely tight

On A3 Industries Xeno True90 AR-15 Pistol Grip

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07/30/25

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Darren H.
Verified Buyer

5.0 star rating

07/29/25

Best looking with exemplary finish lower receiver

Review by Darren H. on 29 Jul 2025 review stating Best looking with exemplary finish lower receiver
Waiting on a few more parts to complete the build. But, this is the best looking billet lower I have seen. All the edges are smooth and the finish is exemplary. Looking forward to finishing the project!

On Sons of Liberty Gun Works / Forward Controls Design AR-15 Ambi Billet Lower Receiver

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07/29/25

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Michael B.
Verified Buyer

5.0 star rating

07/29/25

Outstanding!

Review by Michael B. on 29 Jul 2025 review stating Outstanding!
Outstanding!

On Emissary Development M-LOK Handbrake X - FDE/Black (Rainier Arms Exclusive)

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07/29/25

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$550.00 - $625.00
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Gas Block Diameter .750" Remove This Item
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Caliber 5.56 NATO Remove This Item
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Rail Length 15" Remove This Item

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