AO Precision True Mil-Spec SP/HPT/MPI 5.56 Bolt Carrier Group - BCG556
Only 7 left in stock
Right here is a True Mil-Spec BCG. Each and every bolt, test fired from the factory. 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
| Weight | 11.52 oz |
|---|---|
| Bolt Material | Carpenter 158 Steel |
| Cartridge Compatibility | .223/5.56 NATO/.300 BLK |
| Finish | Mag Phosphate |
| Carrier Profile | M16 |
| High Pressure Tested | HP Tested |
| Magnetic Particle Inspected | Magnetic Partical Inspected |
| Platform | AR-15 |
| Bolt Finish | Mag Phosphate |
| MPN | BCG556 |
| UPC | 4494 |
Compliance
NFA (National Firearms Act) compliance is crucial for legal ownership and transfer of regulated firearms and accessories like short-barreled rifles, suppressors, and certain types of ammunition, ensuring adherence to federal regulations to avoid legal penalties and ensure responsible firearm ownership.
Customer Reviews
- Reviews
- Questions
US
Rock solid BCG!
I purchased this as a backup in the range bag. Decided to run it to test and it ran flawlessly. Cleaned up nice and now sitting in a rifle for regular use and the former BCG is now the spare. Tolerances are fantastic.
USAll the Right Specs at a bargain price.
AO Precision's bolt carrier groups are as good as anyone's, better than most. If you're set on C158 bolts, tool steel extractors, chrome lining where it should be, a phosphate finish, high pressure testing, magnetic particle inspected, why buy anything else?
USExactly what I expected
I am very happy with my purchase. Unlike some of the other reviews my bolt was marked HPT/MPI. Overall this is a great BCG for a really good price. I will definitely order more.
United StatesFit and Finish as Expected, Great Deal
I got a great deal on one of these BCGs a while back from here. Fit and finish is quality, functions flawlessly. I haven’t checked the headspace but I have a feeling it’s spot on. Mine had an upside-down asterisk marking on it, unlike the picture shown here. I contacted AO Precision about it and their response was that it is an internal identifier. I’m assuming something to do with contracts maybe? At any rate, it’s nothing to worry about. These normally sell for a lot more. Snag one already.
United StatesVery well built, and the price was phenomenal!!
In the past Microbest was my reliable choice. Then I seen the specs are identical on the AO precision and when the price dropped I pulled the trigger. I’m very impressed with the quality and will be purchasing more in the near future. Buy with confidence especially at this price.
