Trajectory Arms - BCG 5.56 HP/MPI

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  • Regular price $159.00
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The Trajectory Arms 5.56 Bolt Carrier Group is the core of the operation of the rifle and we take great strides to make it the best we possibly can without any sales gimmicks. Its designed to run as long as hard as possible.

We take great pride in the fact that every 5.56 bolt carrier group is built to exacting specifications and each bolt is individually shot peened, proof tested, and magnetic particle inspected rather than batch testing which is commonly done. This ensures you get and extremely durable and reliable BCG. We also add a Sprinco heavy duty extractor spring to prolong the life of a common wear item and reduce maintenance .

Our BCGs are held to tighter tolerances than most. Carriers that would normally be well within acceptable standards by even higher end manufacturers are rejected by our quality control process. We gauge all of the critical surfaces, and full auto test fire each M4 BCG as an assembly with weak ammo as part of our quality control process. Due to this, parts will show signs of handling such as brass markings or small amounts of carbon.

Although we take great strides to make sure our BCGs are as solid as possible, we want to make sure its the last one you will ever need to buy. Our BCGs are guaranteed for life with a no questions asked warranty. If it doesn’t run for whatever reason, contact us for repair or replacement.

  • Bolt are from Carpenter No. 158® annealed and stress relieved barstock
  • Individually HPT Bolt – High Pressure/Proof Tested
  • Individually MPI Bolt – Magnetic Particle Inspected ASTM EI1444
  • Heat treated and Shot Peened Bolt means less chance of failure
  • Hard Chrome Lined 8620 Carrier – M16/M4 Full Auto profile maintains weight needed for optimal cycling.
  • Hard Chrome Lined Gas Key keeps the the key from wearing out prematurely
  • Gas Key Hardened to USGI Specifications
  • Grade 8 Hardened, M-guns OCKS Fasteners provides a better engagement surface for staking to hold
  • Aggressive gas key staking prevents hardware from coming loose
  • Tool Steel Extractor for a longer lifespan especially with steel cased ammo
  • Sprinco Heavy Duty 5 coil Extractor Spring will likely never need replacement
  • Sprinco enhanced ejector spring is resistant to heat and maintains a longer life cycle
  • 4340 Cam pin is heat treated and coated with solid film lubricant
  • School of the American Rifle inspired directionally marked cam pin helps you install the cam pin the same way after reassembly.
  • Tolerances are held to a .002″ or tighter window for a more efficient, longer lasting BCG
  • Black Extractor Insert
  • Machined to USGI Specifications
  • Manganese Phosphate finish holds lubricants longer, has minimal effect on dimensional tolerances, and wont flake or cause weakness in the core steel.

The Trajectory Arms 5.56 Bolt Carrier Group is the core of the operation of the rifle and we take great strides to make it the best we possibly can without any sales gimmicks. Its designed to run as long as hard as possible.

We take great pride in the fact that every 5.56 bolt carrier group is built to exacting specifications and each bolt is individually shot peened, proof tested, and magnetic particle inspected rather than batch testing which is commonly done. This ensures you get and extremely durable and reliable BCG. We also add a Sprinco heavy duty extractor spring to prolong the life of a common wear item and reduce maintenance .

Our BCGs are held to tighter tolerances than most. Carriers that would normally be well within acceptable standards by even higher end manufacturers are rejected by our quality control process. We gauge all of the critical surfaces, and full auto test fire each M4 BCG as an assembly with weak ammo as part of our quality control process. Due to this, parts will show signs of handling such as brass markings or small amounts of carbon.

Although we take great strides to make sure our BCGs are as solid as possible, we want to make sure its the last one you will ever need to buy. Our BCGs are guaranteed for life with a no questions asked warranty. If it doesn’t run for whatever reason, contact us for repair or replacement.

  • Bolt are from Carpenter No. 158® annealed and stress relieved barstock
  • Individually HPT Bolt – High Pressure/Proof Tested
  • Individually MPI Bolt – Magnetic Particle Inspected ASTM EI1444
  • Heat treated and Shot Peened Bolt means less chance of failure
  • Hard Chrome Lined 8620 Carrier – M16/M4 Full Auto profile maintains weight needed for optimal cycling.
  • Hard Chrome Lined Gas Key keeps the the key from wearing out prematurely
  • Gas Key Hardened to USGI Specifications
  • Grade 8 Hardened, M-guns OCKS Fasteners provides a better engagement surface for staking to hold
  • Aggressive gas key staking prevents hardware from coming loose
  • Tool Steel Extractor for a longer lifespan especially with steel cased ammo
  • Sprinco Heavy Duty 5 coil Extractor Spring will likely never need replacement
  • Sprinco enhanced ejector spring is resistant to heat and maintains a longer life cycle
  • 4340 Cam pin is heat treated and coated with solid film lubricant
  • School of the American Rifle inspired directionally marked cam pin helps you install the cam pin the same way after reassembly.
  • Tolerances are held to a .002″ or tighter window for a more efficient, longer lasting BCG
  • Black Extractor Insert
  • Machined to USGI Specifications
  • Manganese Phosphate finish holds lubricants longer, has minimal effect on dimensional tolerances, and wont flake or cause weakness in the core steel.