Rainier Arms has been putting out a lot of Bolt Carrier Groups lately. This latest version is their Match Grade Nickel Boron. Rainier Arms says that these are machined to higher standards and tolerances than their standard Mil-spec Bolt Carrier Groups. The higher price reflects that machine time. To me this reminds me of the Young Manufacturing National Match Carriers.

Description:

The Rainier Arms Precision Match Grade Nickel Boron BCG 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 tested & Marked to give you ultimate confidence in your weapon system.

Carrier:

Full Auto Carrier
SAE 8620
Heat Treated
Nickel Boron Plated

Bolt:

Carpenter A-158
Shot Peened
Heat Treated
Nickel Boron Plated

Extractor:

Machined from bar
Shot Peened
Heat Treated
Nickel Boron Plated

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
Nickel Boron Plated

Firing Pin Retaining Pin:

Precision bent
Precision cut to length
Heat Treated

Gas Rings:

Stainless Steel per Mil-Spec

Ejector:

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 NiB BCG we offer them with a limited lifetime warranty. So if at anytime your Rainier Arms NiB BCG breaks on your during normal use(Intentional abuse & Gas Key wear not included) we will replace it.