5.56 / 300 BLK Melonited Bolt Carrier Group
5.56 / 300 BLK Bolt Carrier Group (Nitride)

5.56 / 300 BLK Bolt Carrier Group (Nitride)

$134.00

These 5.56 / 300 BLK Bolt Carrier Groups are Melonited, Full-Auto rated, are properly staked, and the bolts are Matched to the barrel. Check your local laws and regulations on ownership guidelines.

Our Rosco Melonited Bolt Carrier Groups are designed to meet the modern-day carbine shooters requirements. We have also balanced input from our consumers and military end users in order to bring you the product you need, not just the one we want to sell you.

(12 customer reviews)

In stock

These 5.56 / 300 BLK Bolt Carrier Groups are Melonited, Full-Auto rated, are properly staked, and the bolts are Matched to the barrel. Check your local laws and regulations on ownership guidelines.

Our Rosco Melonited Bolt Carrier Groups are designed to meet the modern-day carbine shooters requirements. We have also balanced input from our consumers and military end users in order to bring you the product you need, not just the one we want to sell you.

All Rosco BCG’s are to MIL Specification and have a properly staked gas key along with a Melonite coating for extended performance. They also feature a Shot Peened/ MP tested Matched bolt (with upgraded extractor) which is designed to lock up perfectly with our extensions for extreme accuracy. These BCG’s are made to withstand Full-Auto rated fire and unforgiving use from the end user.

Carrier Material: 8620 Steel
Gas Key: 4130 Steel, attached with Grade 8 hardware, properly staked
Cam Pin: Hardened 4340
Firing Pin: 8740 Steel, Mil-Spec, Center-less ground & Hard Chrome coated
Bolt Material: 9310, Properly Heat treated, MPI/HPT
Extractor: 4340 Steel
Ejector: S7 Tool Steel

Additional information

Weight 0.7875 lbs
Dimensions 8 × 1.25 × 1.25 in

12 reviews for 5.56 / 300 BLK Bolt Carrier Group (Nitride)

  1. Kyle Strait (verified owner)

    Just received my BCG yesterday,so I can’t yet comment on reliability, but initial indicators of quality are excellent. Good staking on the gas key, smooth lockup to the barrel, and a slick, even finish on the carrier. Ordered mine along with a 10.5″ 300BLK barrel, and having them matched provides additional peace of mind. Will update after I put some rounds through it, but based on their heritage and experience in the art of manufacturing, I’m proud to have Rosco products in my build.

  2. Waylon Spencer (verified owner)

    Just got this in the mail a week ago. After 1k rounds and no cleaning it’s still grinding through. No issues and out of the box quality is obvious! Great for a build.

  3. Jake Morrow (verified owner)

    Cost effective. My whole front end set-up is Rosco. 11.5″ Bloodline, Gas Block, Gas Tube, and BCG (waiting on those uppers and rails yo)

    The bolt comes and immediately looks high quality. There is a nice smooth slick finish that doesnt have any finish blemishes. No uneven-ness, no scratches, no pits. The matching to my Rosco Barrel Extension is a big plus and a little added confidence. There’s ZERO reason to buy a BCG that is any more expensive.

  4. Chris Dervin (verified owner)

    The bcg is top notch. Everything is staled properly and the finish looks great. So malfunctions with this yet and I don’t think there will be!

  5. Erik Engebretson (verified owner)

    I’m just amazed.

  6. Robbie Pugh (verified owner)

    These guys got their stuff together. Have 2 of their Sauce Packs with 10.5” barrels. Love the products will use them for my future 300 BLK build. Keep up the great work

  7. Simon (verified owner)

    Solid BCG especially for the money. Have shot this suppressed and cyclic full auto repeatedly with no issues so far. Like the rest of their products, you can’t go wrong with Rosco BCG.

  8. Andrew (verified owner)

    You absolutely cannot go wrong with this BCG. It is well staked, has a perfect nitride finish and has functioned flawlessly both suppressed and unsurpassed. I bought it in conjunction with the bloodline 12.5 inch Rosco barrel because they are matched together. Both items came extremely well packed and were in perfect condition. For the price, you will be hard pressed to find a better quality BCG from a better company. Oh, and the bulldog looks awesome on the side.

  9. Justin Hartless (verified owner)

    Solid BCG. Bought this to pair with a Rosco 12.5 barrel that I already had but am repurposing for a new build. If you’re on the fence, don’t be, just buy this BCG. You will be happy you did.

  10. Jim (verified owner)

    I had a Rosco 12.5″ that I wanted to match with bolt carrier and gas/tube combo. I bought the matching components separately and wish they would bring back the sauce packs ! Probably would buy another set just to have (lol). The parts fit perfect as described so far. Full test and review on build when it’s done. All Rosco stuff is top quality feel, dimensions and fit. Mounting the tube to the block was tight but right ! I also checked the dimensions when the block mates to the barrel and found that the block is shouldered next to the barrel. The barrel is dimpled (once) and the spacing appears to be perfectly in line with the opening. A simple check of the block on with no tube attached and verify the opening by viewing from the bottom up (alignment). Thanks Rosco for making a great product(s) and making a custom build simple yet professional.

  11. Timoteo (verified owner)

    I paired the Roscoe BCG with a Roscoe 14.5″ Bloodline barrel and it was a perfect match. The quality, price, and customer service is second to none.

  12. Brandon

    I recently got this in the sauce pack. I can’t attest to long term reliability simply due to not having enough rounds through it, but to this point the sauce pack combo runs very well, and the fit and finish is excellent. So far I am very happy, and am confident it is going to hold up long term. The bulldog on the BCG looks kinda cool with the dust cover open.

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