AO Precision True Mil-Spec SP/HPT/MPI 5.56 Bolt Carrier Group - BCG556

Right here is a True Mil-Spec BCG. This unit is for builders who prefer tried and true manufacturing and aggressive quality assurance testing over fancy coatings, proprietary profiles and laser engraved logos. AO Precision has provided BCGs to large military contractors such as FN America and large commercial retailers who re-brand and sell these at a considerable mark-up. You can now get these directly from AR15Discounts.com and save big!

Bolt

• Machined from Carpenter Technology No. 158 alloy.
• Heat treated
• Shot peened per ASTM B851/SAE AMS2430S
• Individually High Pressure Tested (test fired)
• HP proof testing, 100% using a high pressure M197 or SAAMI commercial equivalent, without evidence of failure
• Individually Magnetic Particle Inspected after Initial Test Fire
• Manganese Phosphate Finish

Extractor

• 4140 Steel per ASTM A108, cold drawn and stress relieved BHN 187-22
• Manganese Phosphate Finish
• Extractor Spring
• Black Extractor Insert
• Viton O-Ring

Carrier

• Machined from AISI 8620 aircraft quality alloy per ASTM A108/A322-13
• Full Mass M16 Profile
• Stress Relieved
• Hard Chrome Bore

Gas Key

• Machined from 4130 chromoly steel alloy per ASTM A108/A322-13
• Grade 8 Hardware
• Properly Staked
• Hard Chrome Internal
• Permatex sealed