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Taking the AR15 parts and accessories to new heightsTM
Rainier Arms, LLC

Rainier Arms AR-15 BCG - Precision Match Grade Phosphate

Rainier Arms BCG - Precision Match Grade Phosphate

Availability: In stock





The Rainier Arms Precision Match Grade Phosphate BCG - 5.56 is machined and finished to a higher standard to meet and exceed all Mil Spec. It is machined using the most precise equipment in the industry. The bolts are MPI/HP tested & Marked to give you ultimate confidence in your weapon system.


  • Full Auto Carrier
  • SAE 8620
  • Heat Treated


  • 5.56/.223
  • Carpenter 158 Steel
  • Shot Peened
  • Heat Treated


  • Machined from bar
  • Shot Peened
  • Heat Treated
  • Maganese Phosphate

Extractor Spring:

  • Chrome Silicone for Longer Life
  • Black Insert as per current Mil-Spec
  • "O" Ring is high temp resistant dark brown

Extractor Retaining Pin:

  • Precision Machined
  • Precision ground to diameter
  • Precision ground to length
  • Heat Treated

Firing Pin:

  • Machined and then precision ground for accuracy
  • Heat Treated

Gas Key Bolt:

  • Precision manufactured in house with extra deep knurling
  • Grade 8
  • 1200 degree locking patch is factory applied to threads to help insure long lasting tightness

Gas key:

  • Hard Chrome lined gas tube as per Mil-Spec
  • Bolts installed to proper torque
  • Staking on both sides of both bolts

Cam Pin:

  • Precision machined
  • Heat Treated

Firing Pin Retaining Pin:

  • Precision bent
  • Precision cut to length
  • Heat Treated

Gas Rings:

  • Stainless Steel per Mil-Spec


  • Precision machined
  • Heat Treated

Ejector Spring:

  • Chrome Silicone
  • Precision ground ends

Ejector Retaining Pin:

  • Precision cut to length
  • Hard Chrome Plated


Limited Lifetime Warranty
We are so confident in our Rainier Arms BCG we offer them with a limited lifetime warranty. So if at anytime your Rainier Arms BCG breaks on your during normal use(Intentional abuse & Gas Key wear not included) we will replace it.

Additional Info

Additional Info

Manufacturer Rainier Arms, LLC
Finish No
Barrel Length No
Caliber No
Configuration No
Option No
Gas Length No
Height No
Rail Length No
Mount No
Profile No
Reticle No
Co Witness No
Size No


Customer Reviews (5)

Needs more attention to detailReview by Treeborne
The gas key had very light staking and was an MIM part so I decided to replace it. Upon removal of the substandard gas key bolts, I met almost no resistance. The threads were devoid of any thread locker and no gasket compound was present between the key and carrier--the latter I realize is not widely used among most manufacturers.

The carrier itself appears to be well machined. I replaced the key with a BCM unit with the correct fasteners with Loctite 262 and Loctite 510 gasket eliminator. It has run fine with no issues. (Posted on 9/7/2016)
A sub-standard BCG at a premium price. Avoid.Review by Al V
I ordered this BCG on 7/13/16. Upon inspection I found that it has a less than desirable MIM carrier key rather than a cast carrier key. In addition the carrier key fasteners are cheap YFS Chinese fasteners. To top it off, the staking on the gas key looked like it was done by a grandmother with arthritis. All in all, you're getting a substandard BCG but are paying Rainier Arms a premium price. It is disappointing to see that Rainier Arms has dropped its quality standards this low. (Posted on 8/1/2016)
No commentReview by Maurice
- (Posted on 5/22/2016)
Functions wellReview by Steve
I can say appearance was good when received. Everything was a it should be as far as assembly and staking. The only complaint I had was the durability of the phosphate coating. I kept it adequately lubed, but had spots where the finish was gone (shiny steel showing with less than 50 rounds thru a new build). Would have given it 5 stars all around if the finish would lasted. Other than that function is superb. (Posted on 5/11/2016)
Great qualityReview by Ron
Fit and finish is great. Bolt and BCG tolerances are very tight. This BCG/bolt is the definition of precision! (Posted on 4/17/2015)

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