Precision Defense™ 5.56 Complete M16 Bolt Carrier Group - Nitride

Manufactured by Precision Defense
Manufactured by Precision Defense
32 Reviews

In Stock

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The Precision Defense™ 5.56 M16 Complete Bolt Carrier Group is machined from high-quality materials to ensure your AR-15 will run reliably as long as you have ammo to shoot it with. The carrier body is machined from 8620 steel and finished in black Nitride for its slick and durable qualities making it run extremely smooth in your receiver. It features an M16 cut allowing it to be full auto rated and the extra weight helps to reduce bolt bounce. The bolt is machined from 9310 steel and magnetic particle inspected to ensure all the dimensions are properly cut to allow for reliable lockup on the locking lugs. The extractor is made from S7 tool steel to withstand thousands of rounds and the gas key is machined from a stock of billet steel with properly staked screws. The Precision Defense 5.56 Bolt Carrier Group is an affordable and reliable option for building an AR whether it is your first or tenth.

  • Compatible with 5.56/.223/.300 BLK
  • Salt Bath Nitride finish
  • 8620 steel carrier with M16 profile
  • 9310 steel bolt face
  • Magnetic particle inspected
  • S7 tool steel extractor
  • Billet gas key with staked screws
  • 4340 cam pin
  • Stainless firing pin
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Bolt FinishSalt Bath Nitride
Bolt Material9310 Steel
BrandPrecision Defense
Caliber Gauge5.56 NATO
Carrier FinishSalt Bath Nitride
Carrier Material8620 Carpenter Steel
Carrier StyleM16 Bolt Carrier
High Pressure TestedUntested
Magnetic Particle InspectMagnetic Particle Inspected
California Prop 65 warning

 WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information go to

Rough machining...

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Kind of a turd... machine marks all over it and I mean ALL over it. I took a gamble and lost. Very rough machining. I'm going to send a few rounds with it and see how it does.

Precision defense bcg


Very nice bcg. Machining is great & the nitride treatment is way better than standard phosphate. Would highly recommend especially for the price

Not bad!

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Picked this BCG up for a budget build I did for a buddy of mine! Fit and finish is ok! Gas key was well staked and despite the somewhat rough tool marks it cycled flawlessly and had zero issues after 200 rounds! I would recommend for budget builds for plinking or as a backup BCG! Reliability will be determined after extended use!


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Bought on labor day sale,recieved today. Does not even slide into my upper reciever tried to force a bit and removed, found scratches down both sides of reciever where i tried to install. Dont waste your time or money, has to be out of spec. Never seen this before.

Can't Go Wrong 300BLK or 5.56

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Picked this up while looking for a spare BCG, caught it on sale for 55, and couldn't be happier with it. It has a nice, solid and smooth nitride job, staked better than some $100+ BCG's which was a surprise. Decided to run it and ended up completing a friend's 300BLK build with it. Has seen and ran smoothly with all types of ammo, 300+ rounds flawlessly so far and can't see that changing any time soon. As always, PA delivers quality for less, thanks for yet another flawless transaction!!! BTW, only 4 Stars because it wouldn't allow me to select 5 Stars, which this product deserves all 5 Stars and then some!!!

Great for the price

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A ok. Not chrome lined but that’s ok for the price

Happy so far

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Ran smooth. This was only around 50 rounds but no issues. Smooth surfaces/finish, no complaints this far. Primary Arms is my first stop when looking for anything.


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Great quality and finish, especially for the price. Haven’t put but a few rounds through it but I cant see a reason why this thing won’t last thousands of more rounds than what I’ll ever put through it. Great bolt especially for someone with several ar15’s this makes for a great spare.

Get what you pay for...

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Spend the extra for a GOOD bolt. It will not run in my new ML AR and I swap out to any other bolt I have and it runs like a top. I it short strokes every time and I even had the range gunsmith check it out and he concurs that it's just a POS. Only reason for 2 stars is that I may have just got a bad one and the fact that it does run in my slightly over gassed CL AR.

Nice BCG

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Great BCG for the money!